JP2005347181A - Fuel cell system and fuel cell system control method wherein hydrogen needed by fuel cell is promptly supplied without excess or insuficiency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which hydrogen needed by a fuel cell 48 can be supplied promptly without excess or insuficiency. <P>SOLUTION: This system is provided with a reformer 40 that forms hydrogen, a hydrogen storage buffer 42 that stores the hydrogen formed by the reformer 40, the fuel cell 48 that generates electric power by the hydrogen, a regulator 46 that supplies the hydrogen accumulated in the hydrogen storage buffer 42 to the fuel cell while keeping pressure of the hydrogen at a target pressure or less, and a control part 50 that stores the hydrogen in the hydrogen storage buffer 42 when an amount of the hydrogen formed by the reformer 40 is more than an amount of the hydrogen consumed by the fuel cell 48, and that supplies the hydrogen to the fuel cell 48 using the regulator 46 in the case the amount of the hydrogen formed by the reformer 40 is less than that of the hydrogen consumed by the fuel cell 48. The control part 50 provides the hydrogen to the fuel cell 48 by controlling the regulator 46 when the pressure of the hydrogen formed by the reformer 40 is lower than a prescribed pressure beforehand. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a fuel cell system control method capable of quickly supplying hydrogen required by a fuel cell without excess or deficiency. In particular, the present invention stores hydrogen in a hydrogen storage buffer when the amount of hydrogen produced by the reformer is greater than the amount of hydrogen consumed by the fuel cell, and the amount of hydrogen produced by the reformer is: The present invention relates to a fuel cell system and a fuel cell system control method for supplying hydrogen to a fuel cell using a regulator when the amount of hydrogen consumed by the fuel cell is smaller.

In a distributed power source using a fuel cell, a fuel reforming type fuel cell system is known. A fuel reforming fuel cell system includes a reformer that generates hydrogen using methanol, gasoline, or the like as fuel, and supplies the hydrogen generated by the reformer to the fuel cell (see, for example, Patent Document 1).
JP 2003-272675 A

  However, the current reformer requires several seconds to change the amount of hydrogen produced. For this reason, when the power consumption changes rapidly, the amount of hydrogen required by the fuel cell cannot be supplied quickly, so the amount of hydrogen produced by the reformer and the fuel cell generate electricity. Unlike the amount of hydrogen required, there were cases where excess or deficiency occurred between the power generated by the fuel cell and the power consumption.

  In addition, the reformer requires several tens of minutes to generate hydrogen at the time of startup. Therefore, when the reformer is stopped when the fuel cell is not generating power, the hydrogen necessary for the fuel cell to start generating power cannot be supplied quickly.

  Also, when the pressure of hydrogen generated by the reformer is lowered to increase the reforming efficiency of the reformer, the amount of hydrogen generated by the reformer is insufficient when the power generated by the fuel cell increases. There is a fear. Conversely, when the pressure of hydrogen generated by the reformer is increased, the reforming efficiency deteriorates. Further, it is not preferable to vary the pressure of hydrogen supplied to the fuel cell because the reaction membrane of the fuel cell may deteriorate. Therefore, it is desirable to maintain the pressure of hydrogen supplied to the fuel cell at an appropriate value without changing the operating conditions of the reformer.

  In order to solve such problems, a fuel cell system according to a first embodiment of the present invention includes a reformer that generates hydrogen, a hydrogen storage buffer that stores hydrogen generated by the reformer, and hydrogen. A fuel cell for generating electricity, a regulator for supplying hydrogen accumulated in the hydrogen storage buffer to the fuel cell while keeping the pressure of hydrogen to be supplied to the fuel cell below the target pressure, and the amount of hydrogen generated by the reformer are as follows: A regulator is used when hydrogen is stored in a hydrogen storage buffer when the amount of hydrogen consumed by the fuel cell is greater and the amount of hydrogen produced by the reformer is less than the amount of hydrogen consumed by the fuel cell. And a controller for supplying hydrogen to the fuel cell.

  When the amount of hydrogen generated by the reformer is greater than the amount of hydrogen consumed by the fuel cell, the control unit stores the hydrogen in the hydrogen storage buffer, and the amount of hydrogen generated by the reformer When the amount of hydrogen consumed by the battery is smaller than the amount of hydrogen consumed, hydrogen is supplied to the fuel cell using the regulator, so that the hydrogen required by the fuel cell can be supplied quickly without excess or deficiency.

  The control unit provides the hydrogen to the fuel cell by controlling the regulator when the pressure of the hydrogen generated by the reformer falls below a predetermined pressure. For this reason, the distortion of the reaction film of the fuel cell due to the pressure difference of the fuel gas can be prevented in advance, and the deterioration due to the distortion of the reaction film of the fuel cell can be suppressed.

  The fuel cell system according to the present embodiment further includes a power measuring device that measures the power consumption of a load that is operated by the power provided from the fuel cell, and the control unit uses the fuel cell to measure the power consumption measured by the power measuring device. When the amount of hydrogen produced by the reformer is smaller than the amount of hydrogen required for power generation, the regulator is controlled to provide hydrogen to the fuel cell. For this reason, only the amount of hydrogen necessary to generate the power consumed by the load can be provided to the fuel cell.

  The control unit controls the regulator to provide hydrogen to the fuel cell when the output voltage of the fuel cell becomes smaller than the reference value. For this reason, when power consumption increases, hydrogen can be rapidly supplied to the fuel cell in order to increase the power generated by the fuel cell.

  The fuel cell system according to the present embodiment further includes a hydrogen pump that pressurizes and accumulates the hydrogen generated by the reformer in the hydrogen storage buffer, and the control unit consumes the amount of hydrogen generated by the reformer by the fuel cell. If the amount of hydrogen to be used is greater, hydrogen is stored in the hydrogen storage buffer using a hydrogen pump. Therefore, even when the hydrogen pressure generated by the reformer is lower than the pressure for accumulating hydrogen in the hydrogen storage buffer when it is necessary to store the hydrogen in the hydrogen storage buffer, the hydrogen storage buffer Can store hydrogen. Further, the output of the reformer can be kept high and the reformer can be continuously driven at an efficiency higher than a predetermined efficiency.

  The controller reduces fluctuations in the operation of the reformer by buffering fluctuations in the amount of hydrogen consumed by the fuel cell using a hydrogen storage buffer. For this reason, the loss of energy that occurs when the output of the reformer is varied can be reduced. The control unit pressurizes and accumulates hydrogen in the hydrogen storage buffer by driving the hydrogen pump when the pressure of hydrogen generated by the reformer exceeds a predetermined pressure. For this reason, the pressure of hydrogen supplied to the fuel cell can be maintained at an appropriate value. Further, it is possible to prevent distortion of the reaction film of the fuel cell due to an increase in the pressure of hydrogen generated by the reformer, and to suppress deterioration due to distortion of the reaction film of the fuel cell.

  When the amount of hydrogen generated by the reformer is larger than the amount of hydrogen required for the fuel cell to generate power consumption measured by the power measurement device, the control unit Is pressurized and accumulated in the hydrogen storage buffer. For this reason, only the amount of hydrogen necessary to generate the power consumed by the load can be provided to the fuel cell.

  When the output voltage of the fuel cell becomes larger than the reference value, the control unit pressurizes and accumulates hydrogen in the hydrogen storage buffer by driving the hydrogen pump. For this reason, when the power consumption is reduced, the amount of hydrogen supplied to the fuel cell can be rapidly reduced in order to reduce the power generated by the fuel cell.

  The controller stores the hydrogen generated by the reformer in the hydrogen storage buffer at night using a hydrogen pump. For this reason, the reformer can be driven with high efficiency even at night when the power consumption is low. The controller continues to operate for the entire day without stopping the reformer. For this reason, the energy loss which arises when starting a reformer can be reduced.

  The fuel cell system according to this embodiment further includes a hydrogen reduction device that generates hydrogen using natural energy, and the hydrogen pump further pressurizes and accumulates the hydrogen generated by the hydrogen reduction device in the hydrogen storage buffer. For this reason, even when the fuel cell consumes all of the hydrogen generated by the reformer, the hydrogen can be stored in the hydrogen storage buffer.

  The hydrogen reduction device further generates hydrogen again using surplus power when the power generated by the fuel cell is larger than the power consumption of the load. For this reason, hydrogen can be stored in the hydrogen storage buffer while maintaining high power generated by the fuel cell and driving the fuel cell with efficiency higher than a predetermined power generation efficiency.

  The fuel cell system according to this embodiment further includes a bypass pipe that supplies the hydrogen generated by the reformer to the fuel cell without passing through the hydrogen storage buffer. For this reason, hydrogen can be supplied to the fuel cell without consuming energy for hydrogen storage and hydrogen release.

  The reformer has a maximum hydrogen production per hour that is less than a maximum hydrogen consumption per hour consumed by the fuel cell. For this reason, a reformer can be reduced in size. In addition, since the reformer is driven in an output region close to the rating, the reformer can be driven with higher efficiency than a predetermined efficiency.

  A fuel cell system control method according to another aspect of the present invention includes a step of generating hydrogen using a reformer, a step of storing hydrogen generated by the reformer in a hydrogen storage buffer, and a regulator. A step of providing hydrogen accumulated in the hydrogen storage buffer to the fuel cell while maintaining the pressure of the hydrogen to be provided to the fuel cell below a target pressure, a step of generating electricity with hydrogen using the fuel cell, and a reformer When the amount of hydrogen produced is greater than the amount of hydrogen consumed by the fuel cell, the hydrogen is stored in a hydrogen storage buffer, and the amount of hydrogen produced by the reformer is less than the amount of hydrogen consumed by the fuel cell. A control step of supplying hydrogen to the fuel cell using a regulator.

  The control step provides the hydrogen to the fuel cell by controlling the regulator when the pressure of the hydrogen generated by the reformer falls below a predetermined pressure. The fuel cell system control method according to the present embodiment further includes a step of measuring the power consumption of a load operated by the power provided from the fuel cell using the power measurement device, and the control step is measured by the power measurement device. When the amount of hydrogen generated by the reformer is smaller than the amount of hydrogen required for the fuel cell to generate electricity, the regulator is controlled to provide hydrogen to the fuel cell. .

  The control step controls the regulator to provide hydrogen to the fuel cell when the output voltage of the fuel cell becomes lower than the reference value. Further, in the fuel cell system control method according to the present embodiment, when the amount of hydrogen generated by the reformer is larger than the amount of hydrogen consumed by the fuel cell, hydrogen is stored in the hydrogen storage buffer using a hydrogen pump.

  The control step reduces fluctuations in the operation of the reformer by buffering fluctuations in hydrogen consumption by the fuel cell using a hydrogen storage buffer. In the control step, when the pressure of hydrogen generated by the reformer exceeds a predetermined pressure, the hydrogen is pressurized and accumulated in the hydrogen storage buffer by driving the hydrogen pump. The control step includes a hydrogen pump when the amount of hydrogen produced by the reformer is greater than the amount of hydrogen required for the fuel cell to generate power, as measured by the power measurement device. Is pressurized and accumulated in the hydrogen storage buffer.

  In the control step, when the output voltage of the fuel cell becomes larger than the reference value, hydrogen is pressurized and accumulated in the hydrogen storage buffer by driving the hydrogen pump. The control step stores the hydrogen generated by the reformer in the hydrogen storage buffer at night using a hydrogen pump. The control step continues to operate for the entire day without shutting down the reformer.

  The fuel cell system control method according to this embodiment further includes a hydrogen reduction step of generating hydrogen by a hydrogen reduction device using natural energy, and the control step further transfers the hydrogen generated by the hydrogen reduction device to a hydrogen storage buffer. Accumulate under pressure.

  The hydrogen reduction step further generates hydrogen again using the surplus power when the power generated by the fuel cell is larger than the power consumption of the load. Further, the fuel cell system control method in this embodiment compares the amount of hydrogen generated by the reformer with the amount of hydrogen consumed by the fuel cell, and the smaller amount of hydrogen is not passed through the hydrogen storage buffer. Supply to the fuel cell using bypass piping.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  According to the present invention, the control unit stores the hydrogen in the hydrogen storage buffer when the amount of hydrogen generated by the reformer is larger than the amount of hydrogen consumed by the fuel cell, and generates hydrogen generated by the reformer. When the amount of hydrogen is smaller than the amount of hydrogen consumed by the fuel cell, hydrogen is supplied to the fuel cell using the regulator, so that the hydrogen required by the fuel cell can be quickly supplied without excess or deficiency.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the development means of the invention.

  FIG. 1 is a diagram illustrating an example of a configuration of a fuel cell system 30 according to an embodiment of the present invention. An object of the present embodiment is to provide a fuel cell system that can quickly supply the hydrogen required by the fuel cell without excess or deficiency.

  The fuel cell system 30 is installed for each residence, for example, and supplies power to each residence.

  The fuel cell system 30 includes a reformer 40, a hydrogen purifier 62, a hydrogen pump 44, a hydrogen storage buffer 42, a regulator 46, a bypass pipe 56, a fuel cell 48, a load 54, and a power measuring device. 52, a hydrogen reduction device 58, a natural energy power generation device 64, and a control unit 50.

  The reformer 40 generates hydrogen. For example, the reformer 40 reforms city gas, propane gas, or the like supplied to each residence to generate hydrogen gas. The hydrogen purifier 62 increases the purity of the hydrogen generated by the reformer 40.

  The hydrogen gas generated by the reformer 40 is supplied to the fuel cell 48 via the hydrogen purifier 62. At this time, the pressure of hydrogen supplied to the fuel cell 48 is set to be about 20 kPa to 200 kPa higher than the atmospheric pressure. This pressure can be set according to the operating conditions of the reformer 40. It is also possible to increase the negative pressure by putting a throttle in the pipe, or to forcibly increase the pressure with a pump. Further, the pressure at the outlet of the hydrogen purifier 62 may be adjusted and set.

  This pressure is not limited, but if the pressure is not more than about 20 kPa higher than atmospheric pressure, there is a possibility that the increased hydrogen consumption when the operating rate of the fuel cell 48 is increased cannot be compensated. Further, at a pressure higher than the atmospheric pressure by about 200 kPa or more, there is a possibility that extra energy may be required, and when this pressure is set according to the operating conditions of the reformer 40, the selectivity of the product in the reforming reaction is high. May decrease.

  The hydrogen generated by the reformer 40 can be purified and used by a hydrogen purification method such as a PSA method, a hydrogen separation membrane method, or a CO selective oxidation method. Each hydrogen purification method is appropriately selected from the scale, the performance of the fuel cell 48, and the like. Increasing the purity of hydrogen using such a hydrogen purification method is advantageous because the operating efficiency of the fuel cell 48 increases.

  The hydrogen purifier 62 of the present embodiment highly enhances the purity of hydrogen by using the PSA method. When the purity of hydrogen is highly increased by the PSA method, the exhaust gas from the fuel cell 48 is reduced, and the hydrogen in the exhaust gas can be reused as the fuel for the fuel cell 48.

  The fuel cell 48 generates power using hydrogen. The fuel cell 48 is, for example, a polymer electrolyte fuel cell (PEFC).

  The load 54 is operated by electric power provided from the fuel cell 48. The power measuring device 52 measures the power consumption of the load 54. In the present embodiment, the power measuring device 52 is a current measuring device as a power measuring device.

  The hydrogen storage buffer 42 stores the hydrogen generated by the reformer 40. The hydrogen storage buffer 42 has a hydrogen storage alloy. The hydrogen storage alloy of a present Example consists of a Ti-Cr-V type alloy, for example. Since the hydrogen storage alloy of the hydrogen storage buffer 42 selectively adsorbs hydrogen, the purity of hydrogen can be increased.

  Further, since the hydrogen storage buffer 42 stores hydrogen, even if the amount of hydrogen generated by the reformer 40 is insufficient compared to the amount of hydrogen required by the fuel cell 48, the hydrogen storage buffer 42. The amount of hydrogen required by the fuel cell 48 can be supplied using the hydrogen stored in the fuel cell 48. Therefore, in the reformer 40 of this embodiment, the maximum hydrogen production amount per hour may be smaller than the maximum hydrogen consumption amount per hour consumed by the fuel cell 48. Thereby, the reformer 40 can be reduced in size.

  The hydrogen pump 44 accumulates hydrogen generated by the reformer 40 in the hydrogen storage buffer 42 under pressure. Further, the hydrogen pump 44 further accumulates the hydrogen generated by the hydrogen reduction device 58 in the hydrogen storage buffer 42 under pressure. Thereby, even when the fuel cell 48 consumes all of the hydrogen generated by the reformer 40, the hydrogen can be stored in the hydrogen storage buffer 42.

  The regulator 46 provides the fuel cell 48 with the hydrogen accumulated in the hydrogen storage buffer 42 while keeping the pressure of the hydrogen provided to the fuel cell 48 below the target pressure.

  The natural energy power generation device 64 generates power using natural energy such as sunlight or wind power.

  The hydrogen reduction device 58 generates hydrogen using natural energy. In the present embodiment, hydrogen is generated using the electric power generated by the natural energy power generation device 64. As a result, even when the fuel cell 48 consumes all of the hydrogen generated by the reformer 40 and the load 54 consumes all of the power generated by the fuel cell 48, the hydrogen is stored in the hydrogen storage buffer 42. Can be stored.

  Further, when the power generated by the fuel cell 48 is larger than the power consumed by the load 54, the hydrogen reduction device 58 generates hydrogen again using the surplus power.

  In general, the fuel cell 48 has higher power generation efficiency as the power generated is higher. Therefore, even when the power consumed by the load 54 is smaller than the power for driving at a higher efficiency than the predetermined power generation efficiency, the power generated by the fuel cell 48 is kept high and higher than the predetermined power generation efficiency. While driving the fuel cell 48 with efficiency, the hydrogen reduction device 58 is driven with surplus power to generate hydrogen, and the hydrogen can be stored in the hydrogen storage buffer 42.

  The bypass pipe 56 supplies the hydrogen generated by the reformer 40 to the fuel cell 48 without passing through the hydrogen storage buffer 42. Thereby, hydrogen can be supplied to the fuel cell 48 without consuming energy for hydrogen storage and hydrogen release.

  The control unit 50 stores the hydrogen in the hydrogen storage buffer 42 when the amount of hydrogen generated by the reformer 40 is larger than the amount of hydrogen consumed by the fuel cell 48, and the hydrogen generated by the reformer 40. When the amount is less than the amount of hydrogen consumed by the fuel cell 48, hydrogen is supplied to the fuel cell 48 using the regulator 46. For this reason, the hydrogen required by the fuel cell 48 can be supplied quickly without excess or deficiency.

  Further, when the amount of hydrogen generated by the reformer 40 is larger than the amount of hydrogen consumed by the fuel cell 48, the control unit 50 stores the hydrogen in the hydrogen storage buffer 42 using the hydrogen pump 44. . Therefore, even when the hydrogen pressure generated by the reformer 40 is lower than the pressure for accumulating hydrogen in the hydrogen storage buffer 42 when hydrogen needs to be stored in the hydrogen storage buffer 42, Hydrogen can be stored in the hydrogen storage buffer 42.

  As described above, the control unit 50 reduces fluctuations in the operation of the reformer 40 by buffering fluctuations in the amount of hydrogen consumed by the fuel cell 48 using the hydrogen storage buffer 42. By reducing fluctuations in the operation of the reformer 40, the reformer 40 can be driven efficiently.

  Generally, in order for the reformer 40 to efficiently generate hydrogen, the reformer 40 needs to maintain an appropriate temperature and stabilize the thermal equilibrium state. In order to change the amount of hydrogen generated by the reformer 40, it is necessary to change the amount of heat given to the reformer 40. However, when the amount of heat given to the reformer 40 is changed, the thermal equilibrium state inside the reformer 40 is changed. Breakage and temperature deviation temporarily increase. For this reason, the reforming efficiency decreases until the thermal equilibrium state is stabilized again.

  However, according to the fuel cell system 30 of the present embodiment, when the control unit 50 uses the hydrogen storage buffer 42 to reduce fluctuations in the operation of the reformer 40, the output of the reformer 40 is varied. Can reduce energy loss.

  FIG. 2 is a diagram illustrating an example of a relationship between output and efficiency in the reformer 40. The horizontal axis represents the ratio of the output to the rating in the reformer 40, and the vertical axis represents the reforming efficiency. In general, the efficiency of the reformer 40 depends on the output of the reformer 40. Therefore, when the reference efficiency that is the lower limit of the efficiency is determined, the lower limit of the output of the reformer 40 is determined so that the efficiency of the reformer 40 is equal to or higher than the reference efficiency.

  In the reformer 40 in the present embodiment, the maximum hydrogen production amount per hour is smaller than the maximum hydrogen consumption amount per hour consumed by the fuel cell 48, so that the reformer 40 is in a power range closer to the rating. Therefore, the reformer 40 can be driven with high efficiency.

  Further, when the output of the reformer 40 is kept high so as to drive the reformer 40 at an efficiency higher than a predetermined efficiency, the amount of hydrogen generated by the reformer 40 is the hydrogen consumed by the fuel cell 48. Even if the amount exceeds this amount, the controller 50 can control the hydrogen pump 44 to store excess hydrogen in the hydrogen storage buffer 42. In this way, fluctuations in the amount of hydrogen consumed by the fuel cell 48 can be buffered using the hydrogen storage buffer 42, so that the fuel cell 48 can be controlled by controlling the reformer 40 to keep the output of the reformer 40 high. Even when the amount of hydrogen consumed by is temporarily reduced, the reformer 40 can be continuously driven at an efficiency higher than a predetermined efficiency.

  Further, the control unit 50 controls the hydrogen generated by the reformer 40 to be stored in the hydrogen storage buffer 42 at night using the hydrogen pump 44. In general, at night, power consumption is less than in the daytime, and the amount of hydrogen required by the fuel cell 48 is less than in the daytime. However, when the reformer 40 continues to be driven at a higher efficiency than the predetermined efficiency at night, the amount of hydrogen produced by the reformer 40 is greater than the amount of hydrogen required by the fuel cell 48. Even when there are many, surplus hydrogen produced by the reformer 40 can be stored in the hydrogen storage buffer 42. Thus, the reformer 40 can be driven with high efficiency even at night when the power consumption is low.

  Further, the control unit 50 determines whether or not to store hydrogen in the hydrogen storage buffer 42 based on the pressure of the generated hydrogen.

  FIG. 3 is a flowchart illustrating an example of the operation of the control unit 50 when determining whether to store hydrogen based on the pressure of the generated hydrogen. The generated hydrogen pressure is compared with the reference pressure (S202). The pressure of hydrogen generated in S202 may be the pressure of hydrogen generated by the reformer 40. Moreover, the pressure of the hydrogen produced | generated in S202 may be the pressure of the hydrogen which the hydrogen purification apparatus 62 supplies.

  If the generated hydrogen pressure exceeds the reference pressure in S202, the amount of hydrogen to be stored in the hydrogen storage buffer 42 is calculated so that the hydrogen pressure does not exceed the reference pressure (S204). Based on the amount of hydrogen to be stored calculated in S204, the hydrogen pump 44 is driven to store hydrogen in the hydrogen storage buffer 42 (S206), and the process ends.

  If the generated hydrogen pressure is lower than the reference pressure in S202, the amount of hydrogen to be supplied from the hydrogen storage buffer 42 is calculated so that the hydrogen pressure does not fall below the reference pressure (S208). Based on the amount of hydrogen to be supplied calculated in S208, the regulator 46 is controlled to supply hydrogen from the hydrogen storage buffer 42 (S210), and the process ends.

  Further, as the reference pressure used for the determination in S202, an upper limit of the reference pressure and a lower limit of the reference pressure may be determined. That is, in S202, when the generated hydrogen pressure exceeds the upper limit of the reference pressure, S204 and S206 are executed, and the process is terminated. In S202, when the generated hydrogen pressure falls below the lower limit of the reference pressure, S208 and S210 are executed, and the process is terminated. In S222, when the generated hydrogen pressure is equal to or higher than the lower limit of the reference pressure and equal to or lower than the upper limit of the reference pressure, the process may be terminated.

  As described above, when the pressure of the hydrogen generated by the reformer 40 is lower than the predetermined pressure, the control unit 50 controls the regulator 46 to provide hydrogen to the fuel cell 48. When the hydrogen pressure generated by the fuel cell exceeds a predetermined pressure, the hydrogen pump 44 is driven to pressurize and accumulate hydrogen in the hydrogen storage buffer 42. Therefore, the pressure of the hydrogen supplied to the fuel cell 48 is set appropriately. Can be kept in value.

  Further, by maintaining the pressure of hydrogen supplied to the fuel cell 48 at an appropriate value, the reaction film of the fuel cell 48 is distorted due to the pressure difference of the fuel gas, and the pressure of hydrogen supplied to the fuel cell 48 is increased. It is possible to prevent the reaction film of the fuel cell 48 from being distorted in advance, and to suppress deterioration due to the distortion of the reaction film of the fuel cell 48.

  In addition, since the control unit 50 can adjust the pressure of hydrogen supplied to the fuel cell 48 by the hydrogen storage buffer 42, the reformer 40 is generated to increase the selectivity of the hydrogen product generated by the reformer 40. Even when the operating rate of the fuel cell 48 is increased while maintaining the hydrogen pressure to be reduced, the increased hydrogen consumption can be supplemented by the hydrogen in the hydrogen storage buffer 42.

  In addition, the control unit 50 compares the power consumption measured by the power measuring device 52 with the amount of hydrogen necessary for the fuel cell 48 to generate power, and the amount of hydrogen generated by the reformer 40 is greater. When the amount of hydrogen is high, hydrogen is pressurized and accumulated in the hydrogen storage buffer 42 by driving the hydrogen pump 44. When the amount of hydrogen generated by the reformer 40 is smaller, the regulator 46 is controlled to supply hydrogen. The fuel cell 48 is provided. At this time, the control unit 50 determines the output voltage of the fuel cell 48 and determines whether or not to store hydrogen in the hydrogen storage buffer 42.

  FIG. 4 is a flowchart illustrating an example of the operation of the control unit 50 when determining whether to store hydrogen based on the output voltage. The voltage output from the fuel cell 48 is compared with the reference voltage (S222).

  If the voltage output from the fuel cell 48 exceeds the reference voltage in S222, the surplus amount of hydrogen is calculated based on the power consumption measured by the power measuring device 52 (S224). Based on the amount of surplus hydrogen calculated in S224, hydrogen is pressurized and accumulated in the hydrogen storage buffer 42 by driving the hydrogen pump 44 (S226), and the process is terminated.

  In S222, when the voltage output from the fuel cell 48 is lower than the reference voltage, the amount of insufficient hydrogen is calculated based on the power consumption measured by the power measuring device 52 (S228). Based on the amount of insufficient hydrogen calculated in S228, the regulator 46 is controlled to supply hydrogen from the hydrogen storage buffer 42 to the fuel cell 48 (S230), and the process is terminated.

  Further, an upper limit of the reference voltage and a lower limit of the reference voltage may be determined as the reference voltage used for the determination in S222. That is, in S222, when the voltage output from the fuel cell 48 exceeds the upper limit of the reference voltage, S224 and S226 are executed, and the process is terminated. In S222, when the voltage output from the fuel cell 48 is below the lower limit of the reference voltage, S228 and S230 are executed, and the process is terminated. In S222, when the voltage output from the fuel cell 48 is equal to or higher than the lower limit of the reference voltage and equal to or lower than the upper limit of the reference voltage, the process may be terminated.

  In this way, the control unit 50 can provide the fuel cell 48 with only the amount of hydrogen necessary to generate the power consumed by the load 54. Further, the control unit 50 determines the output voltage of the fuel cell 48, and when the power consumed by the load 54 increases, the control unit 50 promptly supplies hydrogen to the fuel cell 48 in order to increase the power generated by the fuel cell 48. When the electric power supplied and consumed by the load 54 is reduced, the amount of hydrogen supplied to the fuel cell 48 can be rapidly reduced in order to reduce the electric power generated by the fuel cell 48.

  In general, it takes several seconds to change the amount of hydrogen produced by the reformer 40. However, according to the fuel cell system 30 of the present embodiment, the supply amount of hydrogen to the fuel cell 48 can be controlled using the regulator 46 or the hydrogen pump 44. Therefore, the amount of hydrogen supplied to the fuel cell 48 can be controlled in a shorter time than the time during which the amount of hydrogen generated by the reformer 40 is varied.

  For example, by operating the regulator 46, hydrogen can be supplied to the fuel cell 48 with a response speed within 100 milliseconds. Compared with the response speed of the reformer 40 being about several seconds, the time response supplied to the fuel cell 48 can be greatly improved.

  In general, the power consumed by the load 54 varies in about 10 milliseconds. When the fluctuation speed of the power consumption of the load 54 is faster than the response speed of the regulator 46 and the power generated by the fuel cell 48 is insufficient, the power shortage may be compensated by the secondary battery. Even in such a case, the capacity of the secondary battery can be significantly reduced by providing the hydrogen storage buffer 42.

  FIG. 5 is a diagram showing an example of the time evolution of hydrogen generation and consumption in one day. The horizontal axis represents time, and the vertical axis represents the amount of hydrogen produced per hour or the amount of hydrogen consumed per hour.

  For example, the control unit 50 controls the amount of hydrogen per hour generated by the reformer 40 to be constant throughout the day. In addition, the control unit 50 keeps the reformer 40 operating for the entire day without stopping.

  That is, in the time zone from time t0 to time t1 and in the time zone from time t4 to time t5, the amount of hydrogen per hour generated by the reformer 40 exceeds the amount of hydrogen per hour consumed by the fuel cell 48. . In these time zones, the control unit 50 controls the hydrogen pump 44 while supplying the amount of hydrogen consumed by the fuel cell 48 to the fuel cell 48 using the bypass pipe 56, and the amount generated excessively. Is stored in the hydrogen storage buffer 42.

  In the time period from time t2 to time t3, the amount of hydrogen per hour consumed by the fuel cell 48 exceeds the amount of hydrogen per hour produced by the reformer 40. In these time zones, the control unit 50 controls the regulator 46 while supplying the hydrogen generated by the reformer 40 to the fuel cell 48 using the bypass pipe 56 to store the insufficient amount of hydrogen in the hydrogen storage. It is supplied from the buffer 42.

  Further, in the time zone from time t1 to time t2 and in the time zone from time t3 to time t4, the amount of hydrogen per hour generated by the reformer 40 is the same as the amount of hydrogen per hour consumed by the fuel cell 48. It is. In these time zones, hydrogen generated by the reformer 40 is directly supplied to the fuel cell 48 using the bypass pipe 56.

  Generally, the reformer 40 needs to be warmed up at the time of startup to raise the temperature of the reformer 40. Therefore, when the reformer 40 is stopped, the energy required for warm-up operation at the time of startup is wasted. Further, the warm-up operation requires several tens of minutes, and the reformer 40 cannot supply hydrogen to the fuel cell 48 during that period.

  However, according to the fuel cell system 30 of the present embodiment, the control unit 50 continues to operate for the entire day without stopping the reformer 40, so that the energy loss that occurs when the reformer 40 is started up is reduced. Can be reduced. In addition, by continuously operating the reformer 40, hydrogen can be supplied from the reformer 40 when the fuel cell 48 requires hydrogen.

  FIG. 6 is a diagram illustrating an example of a configuration of a computer 500 included in the control unit 50. In this example, the computer 500 stores a program for causing the fuel cell system to function as the fuel cell system 30 described in FIGS. 1 to 5.

  The computer 500 includes a CPU 700, a ROM 702, a RAM 704, a communication interface 706, a hard disk drive 710, a flexible disk drive 712, and a CD-ROM drive 714. The CPU 700 operates based on programs stored in the ROM 702, the RAM 704, the hard disk drive 710, the flexible disk 720, and / or the CD-ROM 722.

  For example, a program that causes the fuel cell system 30 to function causes the computer 500 to function as the control unit 50 described with reference to FIGS. 1 to 5 to cause the fuel cell system to function.

  The communication interface 706 communicates with, for example, the fuel cell 48, the reformer 40, the hydrogen pump 44, the regulator 46, and the power measuring device 52, receives information regarding each state and transmits a control signal for controlling each of them. To do. The hard disk drive 710, the ROM 702, or the RAM 704 as an example of a storage device stores setting information, a program for operating the CPU 700, and the like. The program may be stored in a recording medium such as the flexible disk 720 and the CD-ROM 722.

  When the flexible disk 720 stores a program, the flexible disk drive 712 reads the program from the flexible disk 720 and provides it to the CPU 700. When the CD-ROM 722 stores a program, the CD-ROM drive 714 reads the program from the CD-ROM 722 and provides it to the CPU 700.

  Further, the program may be read directly from the recording medium into the RAM and executed, or once installed in the hard disk drive 710, the program may be read into the RAM 704 and executed. Further, the program may be stored in a single recording medium or a plurality of recording media. The program stored in the recording medium may provide each function in cooperation with the operating system. For example, the program may request the operating system to perform a part or all of the function and provide the function based on a response from the operating system.

  As a recording medium for storing a program, in addition to a flexible disk and a CD-ROM, an optical recording medium such as a DVD and a PD, a magneto-optical recording medium such as an MD, a tape medium, a magnetic recording medium, an IC card, a miniature card, etc. A semiconductor memory or the like can be used. A storage device such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium.

  As is apparent from the above description, according to the present embodiment, the control unit 50 allows the hydrogen to be stored in the hydrogen storage buffer when the amount of hydrogen generated by the reformer 40 is larger than the amount of hydrogen consumed by the fuel cell 48. When the amount of hydrogen stored in the fuel cell 42 and generated by the reformer 40 is smaller than the amount of hydrogen consumed by the fuel cell 48, hydrogen is supplied to the fuel cell 48 using the regulator 46. The required hydrogen can be supplied quickly without excess or deficiency. When the pressure of the hydrogen generated by the reformer 40 falls below a predetermined pressure, the control unit 50 provides the hydrogen to the fuel cell 48 by controlling the regulator 46, so that the fuel cell due to the pressure difference of the fuel gas. Therefore, it is possible to prevent the reaction film 48 from being distorted, and to suppress deterioration due to the distortion of the reaction film of the fuel cell 48.

  The control unit 50 compares the power consumption measured by the power measuring device 52 with the amount of hydrogen required for the fuel cell 48 to generate power when the amount of hydrogen generated by the reformer 40 is smaller. Since the regulator 46 is controlled to provide hydrogen to the fuel cell 48, only the amount of hydrogen necessary to generate the power consumed by the load 54 can be provided to the fuel cell 48. When the output voltage of the fuel cell 48 becomes smaller than the reference value, the control unit 50 controls the regulator 46 to provide hydrogen to the fuel cell 48. Therefore, when the power consumption increases, the fuel cell 48 generates power. Hydrogen can be quickly supplied to the fuel cell 48 to increase the power to be generated.

  When the amount of hydrogen generated by the reformer 40 is larger than the amount of hydrogen consumed by the fuel cell 48, the control unit 50 stores the hydrogen in the hydrogen storage buffer 42 using the hydrogen pump 44. Even when the hydrogen pressure generated by the reformer 40 is lower than the pressure for accumulating hydrogen in the hydrogen storage buffer 42 when hydrogen needs to be stored in the storage buffer 42, the hydrogen storage buffer 42 Can store hydrogen. Further, the output of the reformer 40 can be kept high, and the reformer 40 can be continuously driven at an efficiency higher than a predetermined efficiency.

  The controller 50 reduces the fluctuation in the operation of the reformer 40 by buffering the fluctuation in the amount of hydrogen consumed by the fuel cell 48 using the hydrogen storage buffer 42, so that the output of the reformer 40 is fluctuated. It is possible to reduce the energy loss that occurs when The controller 50 pressurizes and accumulates hydrogen in the hydrogen storage buffer 42 by driving the hydrogen pump 44 when the pressure of the hydrogen generated by the reformer 40 exceeds a predetermined pressure. The pressure of the supplied hydrogen can be maintained at an appropriate value. For this reason, distortion of the reaction film of the fuel cell 48 due to an increase in the pressure of hydrogen generated by the reformer 40 can be prevented in advance, and deterioration due to distortion of the reaction film of the fuel cell 48 can be suppressed.

  The control unit 50 compares the power consumption measured by the power measuring device 52 with the amount of hydrogen necessary for the fuel cell 48 to generate power when the amount of hydrogen generated by the reformer 40 is larger. Since the hydrogen is pressurized and accumulated in the hydrogen storage buffer 42 by driving the hydrogen pump 44, only the amount of hydrogen necessary for generating the power consumed by the load 54 can be provided to the fuel cell 48.

  The controller 50 pressurizes and accumulates hydrogen in the hydrogen storage buffer 42 by driving the hydrogen pump 44 when the output voltage of the fuel cell 48 becomes larger than the reference value. In order to reduce the power generated by the fuel cell 48, the amount of hydrogen supplied to the fuel cell 48 can be rapidly reduced. Since the controller 50 stores the hydrogen generated by the reformer 40 in the hydrogen storage buffer 42 at night using the hydrogen pump 44, the reformer 40 is driven with high efficiency even at night when the power consumption is low. Can continue.

  Since the control unit 50 continues to operate for the entire day without stopping the reformer 40, it is possible to reduce energy loss that occurs when the reformer 40 is started. Further, since the hydrogen pump 44 pressurizes and accumulates the hydrogen generated by the hydrogen reduction device 58 in the hydrogen storage buffer 42, even when the fuel cell 48 consumes all of the hydrogen generated by the reformer 40, Hydrogen can be stored in the storage buffer 42.

  Furthermore, when the power generated by the fuel cell 48 is larger than the power consumed by the load 54, the hydrogen reduction device 58 generates hydrogen again using the surplus power, so that the power generated by the fuel cell 48 is increased. The hydrogen can be stored in the hydrogen storage buffer 42 while maintaining and driving the fuel cell 48 at an efficiency higher than a predetermined power generation efficiency. Since the bypass pipe 56 supplies the hydrogen generated by the reformer 40 to the fuel cell 48 without passing through the hydrogen storage buffer 42, the fuel cell does not consume energy for hydrogen storage and hydrogen release. 48 can be supplied with hydrogen.

  Since the reformer 40 has a maximum hydrogen production amount per hour smaller than a maximum hydrogen consumption amount per hour consumed by the fuel cell 48, the reformer 40 can be downsized. Moreover, since the reformer 40 is driven in an output region close to the rating, the reformer 40 can be driven with high efficiency.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements are also included in the technical scope of the present invention.

1 shows an exemplary configuration of a fuel cell system 30 according to an embodiment of the present invention. An example of the relationship between output and efficiency in the reformer 40 is shown. It is a flowchart which shows an example of operation | movement of the control part 50 in the case of determining whether to store hydrogen with the pressure of the produced | generated hydrogen. It is a flowchart which shows an example of operation | movement of the control part 50 in the case of determining with an output voltage whether hydrogen is stored. An example of the time evolution of hydrogen production and consumption in a day is shown. It is a figure which shows an example of a structure of the computer 500 which the control part 50 has.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 40 ... Reformer, 42 ... Hydrogen storage buffer, 44 ... Hydrogen pump, 46 ... Regulator, 48 ... Fuel cell, 50 ... Control part, 52 ... Electric power measurement apparatus 54 ... Load, 56 ... Bypass piping, 58 ... Hydrogen reduction device, 30 ... Fuel cell system

Claims (14)

A reformer that produces hydrogen;
A hydrogen storage buffer for storing hydrogen generated by the reformer;
A fuel cell that generates electricity with hydrogen;
A regulator that provides hydrogen accumulated in the hydrogen storage buffer to the fuel cell while maintaining the hydrogen pressure to be provided to the fuel cell below a target pressure;
When the amount of hydrogen produced by the reformer is greater than the amount of hydrogen consumed by the fuel cell, hydrogen is stored in the hydrogen storage buffer, and the amount of hydrogen produced by the reformer is A fuel cell system comprising: a controller that supplies hydrogen to the fuel cell using the regulator when the amount of hydrogen consumed by the fuel cell is smaller than that.   2. The fuel cell system according to claim 1, wherein when the pressure of hydrogen generated by the reformer falls below a predetermined pressure, the control unit provides hydrogen to the fuel cell by controlling the regulator. . A power measuring device for measuring the power consumption of a load that operates with the power provided from the fuel cell;
In the case where the amount of hydrogen generated by the reformer is smaller than the amount of hydrogen necessary for the fuel cell to generate electric power, which is measured by the power measuring device. 3. The fuel cell system according to claim 2, wherein the regulator is controlled to provide hydrogen to the fuel cell.   4. The fuel cell system according to claim 3, wherein the control unit controls the regulator to provide hydrogen to the fuel cell when the output voltage of the fuel cell becomes smaller than a reference value. 5. A hydrogen pump for pressurizing and accumulating hydrogen generated by the reformer in the hydrogen storage buffer;
5. The control unit stores hydrogen in the hydrogen storage buffer using the hydrogen pump when the amount of hydrogen generated by the reformer is larger than the amount of hydrogen consumed by the fuel cell. The fuel cell system described in 1. It further includes a hydrogen reduction device that generates hydrogen using natural energy,
The fuel cell system according to claim 5, wherein the hydrogen pump further pressurizes and accumulates hydrogen generated by the hydrogen reduction device in the hydrogen storage buffer.   The fuel cell system according to claim 6, further comprising a bypass pipe that supplies the hydrogen generated by the reformer to the fuel cell without passing through the hydrogen storage buffer. Using a reformer to generate hydrogen;
Storing the hydrogen produced by the reformer in a hydrogen storage buffer;
Providing the hydrogen stored in the hydrogen storage buffer to the fuel cell while maintaining the pressure of the hydrogen provided to the fuel cell below a target pressure using a regulator;
Using the fuel cell to generate electricity with hydrogen;
When the amount of hydrogen produced by the reformer is greater than the amount of hydrogen consumed by the fuel cell, hydrogen is stored in the hydrogen storage buffer, and the amount of hydrogen produced by the reformer is And a control step of supplying hydrogen to the fuel cell using the regulator when the amount of hydrogen consumed by the fuel cell is smaller than the amount of hydrogen consumed.   The fuel cell system according to claim 8, wherein the control step provides the fuel cell with hydrogen by controlling the regulator when the pressure of hydrogen generated by the reformer falls below a predetermined pressure. Control method. The method further comprises the step of measuring the power consumption of a load operated by the power provided from the fuel cell using a power measuring device,
In the control step, when the amount of hydrogen generated by the reformer is smaller than the amount of hydrogen required for the fuel cell to generate electric power, measured by the power measuring device The fuel cell system control method according to claim 9, further comprising: supplying the hydrogen to the fuel cell by controlling the regulator.   11. The fuel cell system control method according to claim 10, wherein in the control step, when the output voltage of the fuel cell becomes smaller than a reference value, the regulator is controlled to provide hydrogen to the fuel cell.   The control step stores hydrogen in the hydrogen storage buffer using a hydrogen pump when the amount of hydrogen generated by the reformer is larger than the amount of hydrogen consumed by the fuel cell. The fuel cell system control method described. A hydrogen reduction step of generating hydrogen by a hydrogen reduction device using natural energy;
The fuel cell system control method according to claim 12, wherein the control step further pressurizes and accumulates hydrogen generated by the hydrogen reduction device in the hydrogen storage buffer.   The control step compares the amount of hydrogen generated by the reformer with the amount of hydrogen consumed by the fuel cell, and bypasses the smaller amount of hydrogen without passing through the hydrogen storage buffer. The fuel cell system control method according to claim 13, wherein the fuel cell system is supplied to the fuel cell using a pipe.

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