JP4516362B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system including a fuel cell, and more particularly to control at the time of startup of the fuel cell.

  In this fuel cell system, a fuel cell 10 that supplies fuel and oxidant gas to a fuel electrode and an oxidant electrode, respectively, and generates electric power by their chemical reaction, and a power generation line that converts the power generation output of the fuel cell 10 into AC power An inverter 11 supplied to the fuel cell 10, a heat medium circulation circuit 20 in which a heat medium that exchanges heat between the fuel cell 10 circulates, a circulation means 24 that is provided on the heat medium circulation circuit 20 and circulates the heat medium, and heat There is known one provided with a heat medium heating means 32 provided on the medium circulation circuit 20 and energized to raise the temperature of the heat medium (see Patent Document 1).

  In the fuel cell system described in Patent Document 1, moisture is generated inside the fuel cell with power generation. In addition, the fuel cell humidifies the reformed gas and air supplied to the fuel cell in order to ensure the function of the electrolyte interposed between the fuel electrode and the air electrode. In a low temperature environment, there is a problem that the moisture freezes and the fuel cell does not start or the output decreases, and in order to cope with this, a part of the fuel cell is heated intensively with an electric heater or the like. Some start-up methods have been implemented in which power generation is possible in some of them, and the remaining portions are heated using self-heating generated by the partial power generation. Specifically, when the fuel cell temperature Tfc is lower than the operable temperature (fuel cell bypass temperature Tfb), it is heated by the electric heater 32. Is further heated by self-heating by the power generation and heating by the electric heater 32, and when the temperature exceeds the radiator bypass temperature Trb, it is determined that the entire fuel cell can generate power, and control during steady operation is performed. Yes.

  Also, as a method for starting the fuel cell system, fuel gas is supplied to generate power from the fuel cell, and the generated temperature is used to heat a load heating heater that is an internal load. In the start-up method of the portable fuel cell power source that raises the temperature of the battery, while the temperature rises and the battery current increases to the upper limit value, the internal voltage is increased according to the increase of the battery current so that the battery voltage is maintained at the lower limit value. A voltage reference control step for controlling the load, and a current reference control step for controlling the internal load in accordance with an increase in the battery voltage so that the battery current is maintained at the upper limit value after the battery current reaches the upper limit value; Is known (see Patent Document 2).

In the starting method of the fuel cell system described in Patent Document 2, the battery current increases so that the battery voltage is maintained at the lower limit value until the battery current reaches the upper limit value after the temperature rise of the load starts. Since the internal load is controlled according to the power, the maximum load is supplied at each moment. On the other hand, after the battery current reaches the upper limit value, the battery current is maintained at the upper limit value. Since the internal load is controlled according to the increase of the battery voltage, the maximum power generation amount of the fuel cell power supply is supplied to the load. That is, the maximum electric power that can be output by the fuel cell is generated until the temperature of the fuel cell rises to the operating temperature. Further, all the power generation output of the fuel cell is consumed by a heater which is an internal load.
Japanese Patent Laying-Open No. 2003-249251 (page 7-9, FIGS. 1 and 3) Japanese Patent Application Laid-Open No. 07-29585 (page 2-3, FIG. 1-7)

  In the fuel cell system described in Patent Document 1 described above, the self-heat generation amount of the fuel cell 10 is small in the low power generation output region, and thereby the temperature rise of the heat medium (cooling water) of the fuel cell 10 is slow and long time. However, there was a problem that the temperature of the heat medium became lower than the specified temperature, resulting in a decrease in power generation efficiency. Further, in the fuel cell system described in Patent Document 1 described above, since all the power generation output at the time of temperature rise is used for the heater, the user can use the power generation output until the fuel cell is warmed up. There wasn't. On the other hand, when all the power generation output is supplied to the user, it takes time to complete the warm-up of the fuel cell, which causes a problem that power generation efficiency is reduced.

  The present invention has been made to solve the above-described problems. When the fuel cell system generates low power output, the fuel cell can be warmed up quickly and the required power of the user can be satisfied without causing a decrease in power generation efficiency. It aims at providing the fuel cell system which can achieve coexistence with.

In order to solve the above problems, the structural feature of the invention according to claim 1 is that fuel is supplied to the fuel electrode, oxidant gas is supplied to the oxidant electrode, and a fuel cell that generates electric power by their chemical reaction; In a fuel cell system comprising a hot water storage tank that stores water and a power supply line that supplies power generation output of the fuel cell, heating means for raising the temperature of the fuel cell, power generation output detection means for detecting the power generation output of the fuel cell, User power consumption detection means for detecting user power consumption consumed by the power line, and hot water in the hot water storage tank until the power exceeding the user power consumption can be supplied when the fuel cell system is started. If the fuel cell system can be heated to control the power generation output and power that exceeds the user power consumption can be supplied, the user power consumption of the power generation output will be reduced. Control means for controlling the excess power to be supplied to the heating means, and fuel cell temperature detection means for detecting the temperature of the fuel cell, wherein the control means generates power when the predetermined condition is satisfied. The first power generation control means for controlling the power generation output of the fuel cell so as to obtain a predetermined power generation amount, determination means for determining whether or not the power generation output exceeds the user power consumption, and power generation by the determination means When it is determined that the output exceeds the power consumption of the user, the energization start unit that starts energizing the heating unit, and the temperature of the fuel cell detected by the fuel cell temperature detection unit becomes 60 ° C. or higher, at that time And a second power generation control means for controlling the power generation output of the fuel cell so as to follow the user power consumption after the time point.

In addition, the structural feature of the invention according to claim 2 is that, in claim 1, the heat medium that exchanges heat with the fuel cell circulates, and the heat medium exchanges heat with the hot water in the hot water storage tank. And a heat medium circulation circuit for exchanging heat in the heat medium and a circulation means provided on the heat medium circulation circuit for circulating the heat medium, and the heating means is provided on the heat medium circulation circuit and energized to be heated. It is a heat medium heating means for raising the temperature.

The structural feature of the invention according to claim 3 is that, in claim 2 , the heat medium temperature detecting means for detecting the temperature of the heat medium is adopted as the fuel cell temperature detecting means.

In the invention according to claim 1 configured as described above, the control unit controls the power generation output when starting the fuel cell system, and supplies the heating unit with the power exceeding the user power consumption among the power generation output. To control. Thus, when the fuel cell system starts up, when the fuel cell system outputs low power, the fuel cell is quickly warmed by heating by the heating means supplied with excess power in addition to self-heating due to the low power output. Therefore, it is possible to improve the power generation efficiency. Therefore, since the power generation output of the fuel cell is supplied to the user and used for the early warm-up of the fuel cell, both the early warm-up of the fuel cell and the satisfaction of the user's required power can be achieved.
Further, the first power generation control means starts the power generation of the fuel cell when a predetermined condition is satisfied, and controls the power generation output of the fuel cell so that the predetermined power generation amount is obtained. It is determined whether or not the electric power has been exceeded, and the energization start unit starts energizing the heating unit when the determination unit determines that the power generation output has exceeded the user power consumption. As a result, it is possible to reliably secure the power necessary for the user and efficiently warm up the fuel cell using the surplus power.
Further, when the temperature of the fuel cell detected by the fuel cell temperature detecting means becomes 60 ° C. or higher, the energization stopping means stops energization to the heating means at that time, and the second power generation control means Thereafter, the power generation output of the fuel cell is controlled so as to follow the user power consumption. As a result, when the temperature of the fuel cell reaches the energization stop temperature, the power generation output is accurately controlled to the user power consumption, so that the optimum power generation output and temperature control can be performed.

In the invention according to claim 2 configured as described above, in the invention according to claim 1, the heat medium exchanging heat with the fuel cell circulates , and the heat medium is between the hot water in the hot water tank. And a heat medium circulation circuit for exchanging heat with the heat exchanger, and a circulation means provided on the heat medium circulation circuit for circulating the heat medium. The heating means is provided on the heat medium circulation circuit and is energized. Thus, the temperature of the fuel cell can be adjusted easily and accurately by the heat medium heating means for raising the temperature of the heat medium.

In the invention according to claim 3 configured as described above, in the invention according to claim 2 , the fuel cell temperature detecting means employs the heat medium temperature detecting means for detecting the temperature of the heat medium. Can be detected easily and accurately.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a fuel cell 10 and a reformer 20 that generates a reformed gas containing hydrogen gas necessary for the fuel cell 10.

  The fuel cell 10 includes a fuel electrode 11, an air electrode 12 that is an oxidant electrode, and an electrolyte 13 interposed between the electrodes 11 and 12, and supplies the reformed gas supplied to the fuel electrode 11 and the air electrode 12. Electric power is generated using air (cathode air), which is the oxidant gas. A supply pipe 61 that supplies air and a discharge pipe 62 that discharges cathode off-gas are connected to the air electrode 12 of the fuel cell 10. Air is humidified in the middle of the supply pipe 61 and the discharge pipe 62. A humidifier 14 is provided. The humidifier 14 is of a water vapor exchange type and dehumidifies water vapor in the gas discharged from the discharge pipe 62, that is, from the air electrode 12, and supplies the water vapor into the supply pipe 61, that is, air supplied to the air electrode 12. And humidify. Note that air-enriched gas may be supplied instead of air.

  The reformer 20 steam-reforms the fuel and supplies a hydrogen-rich reformed gas to the fuel cell 10, and includes a burner 21, a reforming unit 22, a carbon monoxide shift reaction unit (hereinafter referred to as a CO shift unit). 23) and a carbon monoxide selective oxidation reaction part (hereinafter referred to as CO selective oxidation part) 24. Examples of the fuel include natural gas, LPG, kerosene, gasoline, methanol, and the like. In the present embodiment, description will be made on natural gas.

  The burner 21 is supplied with combustion fuel and combustion air from the outside during start-up, or anode off-gas (reformed gas discharged to the fuel cell and not used) from the fuel electrode 11 of the fuel cell 10 during steady operation. Is supplied, the supplied gas is combusted, and the combustion gas is led out to the reforming unit 22. This combustion gas heats the reforming section 22 (so that it becomes the activation temperature range of the catalyst of the reforming section 22), and then the water vapor contained in the combustion gas is condensed through the combustion gas condenser 34. And exhausted to the outside.

  The reforming unit 22 reforms a mixed gas obtained by mixing the fuel supplied from the outside with the water vapor (reformed water) from the evaporator 25 by using a catalyst charged in the reforming unit 22 to generate hydrogen gas and carbon monoxide. Gas is generated (so-called steam reforming reaction). At the same time, carbon monoxide and steam generated by the steam reforming reaction are converted into hydrogen gas and carbon dioxide (so-called carbon monoxide shift reaction). These generated gases (so-called reformed gas) are led to the CO shift unit 23.

  The CO shift unit 23 is converted into hydrogen gas and carbon dioxide gas by reacting carbon monoxide and water vapor contained in the reformed gas with a catalyst filled therein. Thus, the reformed gas is led to the CO selective oxidation unit 24 with the carbon monoxide concentration reduced.

  The CO selective oxidation unit 24 generates carbon dioxide by reacting carbon monoxide remaining in the reformed gas and CO oxidation air further supplied from the outside with a catalyst filled therein. . Thereby, the reformed gas is led to the fuel electrode 11 of the fuel cell 10 with the carbon monoxide concentration further reduced (10 ppm or less).

  The evaporator 25 is disposed in the middle of the reforming water supply pipe 68 having one end disposed in the water reservoir 50 and the other end connected to the reforming unit 22. The reforming water supply pipe 68 is provided with a reforming water pump 53. The pump 53 is controlled by a control device 90 and pumps recovered water used as reforming water in the water reservoir 50 to the evaporator 25. The evaporator 25 is heated by, for example, the combustion gas discharged from the burner 21, the heat of the reforming unit 22, the CO shift unit 23, and the like, thereby steaming the reformed water fed under pressure.

  A condenser 30 is provided in the middle of a pipe 64 that connects the CO selective oxidation unit 24 of the reformer 20 and the fuel electrode 11 of the fuel cell 10. The condenser 30 is an integral structure in which a reformed gas condenser 31, an anode off gas condenser 32, a cathode off gas condenser 33, and a combustion gas condenser 34 are integrally connected. The reformed gas condenser 31 condenses water vapor in the reformed gas supplied to the fuel electrode 11 of the fuel cell 10 flowing in the pipe 64. The anode off-gas condenser 32 is provided in the middle of a pipe 65 that communicates the fuel electrode 11 of the fuel cell 10 and the burner 21 of the reformer 20, and the fuel electrode 11 of the fuel cell 10 that flows in the pipe 65. Water vapor in the anode off-gas discharged from is condensed. The cathode offgas condenser 33 is provided downstream of the humidifier 14 in the discharge pipe 62, and condenses the water vapor in the cathode offgas discharged from the air electrode 12 of the fuel cell 10 flowing in the discharge pipe 62.

  The above-described condensers 31 to 34 communicate with the deionizer 40 via the pipe 66 so that the condensed water condensed in each of the condensers 31 to 34 is led out to the deionizer 40 and collected. It has become. The deionizer 40 converts the condensed water supplied from the condenser 30, that is, the recovered water into pure water using a built-in ion exchange resin, and leads the purified water to the water reservoir 50. The water reservoir 50 temporarily stores the recovered water derived from the pure water device 40 as reformed water. Further, a pipe for introducing makeup water (tap water) supplied from a tap water supply source (for example, a water pipe) is connected to the deionizer 40, and the amount of water stored in the deionizer 40 is below the lower limit water level. And tap water is supplied.

  The fuel cell system includes a first heat exchanger 71, a heat medium circulation circuit 72 that is provided between the first heat exchanger 71 and the fuel cell 10 and circulates a first heat medium (which is a heat medium). A first pump (circulation means) 73 for circulating the first heat medium is provided on the heat medium circulation circuit 72. Thereby, when the first heat medium passes through the fuel cell 10, heat exchange is performed between the first heat medium and the fuel cell 10. In addition, a heater 78 (electric heater) that is a heat medium heating means (heating means: means for heating the fuel cell 10) that is energized to raise the temperature of the first heat medium is provided on the heat medium circulation circuit 72. Is provided. The heater 78 is a heater whose electric resistance is variable, and controls the electric resistance of the heater 10 according to the difference between the power generation output of the fuel cell 10 and the user power consumption. Further, a temperature sensor 85 that is a heat medium temperature detecting means (fuel cell temperature detecting means) for detecting the temperature of the first heat medium is provided in the vicinity of the outlet of the fuel cell 10 of the heat medium circulation circuit 72. The control device 90 inputs the temperature of the first heat medium detected by the temperature sensor 85 and controls energization / non-energization of the heater 78 and the electric resistance of the heater 78 based on the temperature.

  The fuel cell system also includes a hot water storage tank 74 that is a hot water storage tank for storing hot water. This hot water tank 74 is provided with one columnar container, in which hot water is stored in layers, that is, the temperature of the upper part is the highest and lower as it goes to the lower part, and the lower part is the lowest. It has come to be. The lower part of the columnar container of the hot water tank 74 is replenished with water (low temperature water) such as tap water, and the hot hot water stored in the hot water tank 74 is led out from the upper part of the columnar container of the hot water tank 74. ing. Between the 1st heat exchanger 71 and the hot water storage tank 74, the warm water circulation circuit 75 in which the warm water which is a 2nd heat medium is circulated, and the 2nd pump 76 which circulates warm water on the warm water circulation circuit 75 are provided. . One end and the other end of the hot water circulation circuit 75 are connected to an upper part and a lower part of the hot water tank 74. The second pump 76 sucks the low temperature hot water at the lower part of the hot water tank 74 and passes it through the hot water circulation circuit 75 and discharges it to the upper part of the hot water tank 74, or sucks the hot water at the upper part of the hot water tank 74. The hot water circulation circuit 75 is caused to pass through and discharged to the lower part of the hot water storage tank 74.

  A second heat exchanger 82 is provided on the hot water circulation circuit 75. A condenser heat medium circulation circuit 83 for circulating the condenser heat medium is provided between the second heat exchanger 82 and the condenser 30. A third pump 84 for circulating the condenser heat medium is provided on the condenser heat medium circulation circuit 83. Accordingly, in the second heat exchanger 82, heat exchange is performed between the condenser heat medium passing through the condenser heat medium circulation circuit 83 and the hot water passing through the hot water circulation circuit 75, and the The hot water is heated by the high-temperature condenser heat medium.

  Further, the fuel cell system includes an inverter 45. The inverter 45 converts the power generation output of the fuel cell 10 into AC power and supplies it to a power supply line (AC power supply line) 46. The power line 46 is a line for supplying AC power used as a commercial power source to the user, and the user uses the electrical product by connecting the electrical product to the power line 46. Further, the inverter 45 steps down or boosts the power generation output and supplies it to a power line (DC power line) 47. The power line 47 is a line for supplying direct current power to so-called auxiliary equipment such as pumps 73, 76, 83 that are constituent members of the fuel cell 10, valves (not shown), an ignition device for the burner 21, and a heater 78. It is. The inverter 45 has a function of detecting the power generation output of the fuel cell 10, and further has a function of detecting an electrical load of the power supply lines 46 and 47, that is, power consumption consumed by the lines 46 and 47. The power consumption consumed by the power line 46 is particularly referred to as user power consumption.

  Further, the temperature sensor 85, the first to third pumps 73, 76, 83, the inverter 45, and the heater 78 described above are connected to the control device 90 (see FIG. 2). The control device 90 has a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected via a bus. The CPU executes a program corresponding to the flowchart of FIG. 3 to control the power generation output of the fuel cell 10 when starting the fuel cell system, and to the heater 78 the power exceeding the user power consumption among the power generation output. The supply control is executed. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  Next, the operation of the above-described fuel cell system will be described with reference to FIGS. When a start switch (not shown) is turned on, the control device 90 executes the program shown in FIG. In step 102, activation of the fuel cell system is started. Specifically, combustion fuel and combustion air are supplied to the burner 21 and burned. When the reforming unit 22 reaches a predetermined temperature by heating the combustion gas, fuel and reforming water are supplied to the reforming unit 22. Further, oxidation air is supplied to the CO selective oxidation unit 24. However, the reformed gas derived from the reformer 20 is not supplied to the fuel cell 10.

  Further, the control device 90 detects the coolant temperature Th of the fuel cell by the temperature sensor 85, and increases the temperature of the coolant that is the first heat medium based on the temperature (steps 104 and 106). Specifically, the temperature of the low-temperature cooling water immediately after start-up is raised using the hot water in the hot water tank 74. That is, the second pump 76 is driven to send hot hot water from the upper part of the hot water tank 74 to the first heat exchanger 71. Further, the first pump 73 is driven to send the cooling water in the fuel cell 10 to the first heat exchanger 71. Thereby, the temperature of the cooling water is raised by the first exchanger 71 with the hot water.

  Then, after the time when the coolant temperature Th of the fuel cell 10 reaches the first specified temperature T1 (time t1 in FIG. 4), the time when the warming-up of the reformer 20 is completed (time t2 in FIG. 4). ), The power generation of the fuel cell 10 is started (steps 108 to 112). In step 108, it is determined whether or not the cooling water temperature Th has reached the first specified temperature T1, and the processing of steps 104 to 108 is repeatedly executed until it reaches, and if it reaches, the program is advanced to step 110. In step 110, it is determined whether or not the warming-up of the reformer 20 has been completed. The processes in steps 104 to 110 are repeatedly executed until the warming-up is completed. In determining whether the warm-up is complete, for example, if the inside of the CO selective oxidation unit 24 has reached a predetermined temperature, it is determined that the warm-up is completed. If the warm-up is completed, it is determined that the amount of hydrogen and the carbon monoxide concentration in the reformed gas derived from the reformer 20 have reached specified values. The first specified temperature T1 is defined as the temperature of the first heat medium at which the water balance in the fuel electrode or air electrode of the fuel cell 10 becomes zero with respect to the desired generated current value of the fuel cell 10. And is stored in the storage unit 91 of the control device 90 in advance.

  In step 112 (first power generation control means), the control device 90 supplies the reformed gas derived from the reformer 20 to the fuel cell 10 and starts power generation of the fuel cell 10. That is, when the above-described predetermined condition is satisfied, the power generation output of the fuel cell 10 is controlled so that the power generation of the fuel cell 10 is started and the predetermined power generation amount is obtained. The predetermined power generation amount is a preset first target power generation amount after the start of startup, and is set to be equal to or less than the maximum output power of the fuel cell 10. Specifically, after time t2, the power generation output gradually increases until reaching a predetermined power generation amount regardless of the user power consumption (user load power), and the power generation amount is maintained after reaching the predetermined power generation amount. To generate electricity. As a result, the self-heating value can be increased and the warm-up time can be shortened as much as possible without causing the fuel cell 10 to generate more power than possible without causing damage.

  As described above, when the power generation of the fuel cell 10 is started, the temperature of the fuel cell 10 is increased by self-heating by the power generation. In addition to the temperature increase of the cooling water using the hot water in the hot water tank 74 described above, the cooling water further increases. Be warmed. In this way, if the power generation output of the fuel cell 10 exceeds the user power consumption (user load power) while the temperature of the cooling water is raised by self-heating, the temperature of the cooling water is raised even by heating by the heater 78. Specifically, in step 114, the control device 90 detects the power generation output of the fuel cell 10 by the inverter 45, and in step 116, whether the detected power generation output is equal to or greater than the user load power, that is, the power generation output is consumed by the user. It is determined whether or not the power has been exceeded (determination means). In step 118 (energization start means), when it is determined in step 116 that the power generation output exceeds the user power consumption, energization of the heater 78 is started (time t3 in FIG. 4). Thereby, since the heating by the heater 78 is further applied, the temperature rise of the cooling water is further accelerated.

  Thus, while the fuel cell 10 is warmed up by the self-heating and the heater 78, the control device 90 detects the cooling water temperature Th of the fuel cell 10 by the temperature sensor 85 (step 120), and cools the fuel cell 10. When the water temperature Th reaches the second specified temperature T2 (for example, 60 ° C.) that is the energization stop temperature (time t4 in FIG. 4), the energization to the heater 78 is stopped at that time (step 122). Steps 120 and 122 are energization stop means. Further, after the time when the coolant temperature Th of the fuel cell 10 reaches the second specified temperature T2, the control device 90 controls the power generation output of the fuel cell 10 so as to follow the user power consumption (step 126: Second power generation control means). It should be noted that the second specified temperature T2 is set to a temperature at which the influence of carbon monoxide poisoning and the like is small even when the temperature is operated for a long time.

  Then, the control device 90 detects the coolant temperature Th of the fuel cell by the temperature sensor 85 (step 128), and when the coolant temperature Th of the fuel cell reaches a steady operation temperature Tb (for example, 80 ° C.) (FIG. 4). Thereafter, the cooling water temperature Th is adjusted to be maintained at the steady operation temperature Tb until the system is stopped (steps 126 to 132). Specifically, when the cooling water (heat medium) in the fuel cell 10 is higher than the steady operation temperature Tb, the second pump 76 is driven to supply the low temperature hot water from the lower part of the hot water tank 74 to the first heat exchanger. 71, the first pump 73 is driven, and the cooling water (heat medium) in the fuel cell 10 is allowed to flow through the first heat exchanger 71, whereby the temperature of the cooling water in the fuel cell 10 is lowered. The steady operation temperature Tb is set to a temperature at which high efficiency is obtained.

  For example, in the case where the user load power is low, if the follow-up control that follows the user load power after the start of power generation is performed without applying the present invention, the coolant temperature of the fuel cell 10 as shown in FIG. Since the power generation output is low, self-heating is small and the temperature rises only gradually, so the power generation efficiency is not good. However, as can be understood from the above description, in this embodiment, when the fuel cell system is started, the control device 90 controls the power generation output, and the power that exceeds the user power consumption in the power generation output is heated. 78. As a result, when the fuel cell system starts up at a low power generation output, the fuel cell 10 is promptly moved by heating by the heater 78 supplied with excess power in addition to self-heating due to the low power generation output. Since it can be warmed up, heat recovery hot water temperature and power generation efficiency can be improved. Therefore, since the power generation output of the fuel cell 10 is supplied to the user and used for the early warm-up of the fuel cell 10, both the early warm-up of the fuel cell 10 and the satisfaction of the user's required power can be achieved. .

  Further, the first power generation control means (step 112) starts the power generation of the fuel cell 10 when a predetermined condition is satisfied, and controls the power generation output of the fuel cell 10 so that the predetermined power generation amount is obtained, and the determination means (step 114, 116) determines whether or not the power generation output exceeds the user power consumption, and the energization start means (step 118) causes the heater 78 when the power generation output exceeds the user power consumption by the determination means. Start energization. As a result, it is possible to reliably secure the power necessary for the user and efficiently warm up the fuel cell using the surplus power.

  Further, when the temperature of the detected heat medium becomes equal to or higher than the power supply stop temperature, the power supply stopping means (step 124) stops the power supply to the heat medium heating means at that time, and the second power generation control means (step 126). ) Controls the power generation output of the fuel cell 10 so as to follow the user power consumption after that time. As a result, when the first heat medium temperature reaches the energization stop temperature, the power generation output is accurately controlled to the user power consumption, so that the optimum power generation output and temperature control can be performed.

  The heater 78 is a heater whose electric resistance is variable. By controlling the electric resistance of the heater 78 in accordance with the difference between the power generation output of the fuel cell 10 and the user power consumption, surplus exceeding the user power consumption is achieved. Electric power can be reliably and accurately supplied to the heater 78 without waste.

  In the embodiment described above, a mechanism for raising the temperature of the fuel cell 10 using a heat medium including the heat medium heating means (heater 78) is employed as the heating means for raising the temperature of the fuel cell 10. If it does, it will not be restricted to such a mechanism, For example, you may make it employ | adopt the mechanism which heats up the fuel cell 10 directly with a heater.

  In the above-described embodiment, the temperature sensor 85 that detects the temperature of the heat medium that raises the temperature of the fuel cell 10 is employed as the fuel cell temperature detection means that detects the temperature of the fuel cell 10. You may make it employ | adopt the temperature sensor which detects the temperature of 10 directly.

  Further, in the above-described embodiment, the heat medium heating means may be configured by other than the heater 78 as long as it is provided on the heat medium circulation circuit 72 and energized to raise the temperature of the heat medium. .

  In the above-described embodiment, the heat medium circulation circuit 72 in which the heat medium that exchanges heat with the fuel cell 10 circulates, and the circulation means that is provided on the heat medium circulation circuit 72 and circulates the heat medium ( And the heating means is a heat medium heating means (heater 78) provided on the heat medium circulation circuit 72 and energized to raise the temperature of the heat medium, thereby adjusting the temperature of the fuel cell 10. Can be implemented easily and accurately.

  In the above-described embodiment, the heat medium temperature detecting means (temperature sensor 85) for detecting the temperature of the heat medium is adopted as the fuel cell temperature detecting means, so that the temperature of the fuel cell 10 can be detected easily and accurately. can do.

  In the above-described embodiment, the heater 78 is a heater having a fixed electric resistance, and controls the power supplied to the heater 78 so as to be the difference between the power generation output of the fuel cell 10 and the user power consumption. You may do it. As a result, surplus power exceeding the user power consumption can be reliably and accurately supplied to the heater 78 without waste.

1 is a schematic diagram showing an outline of an embodiment of a fuel cell system according to the present invention. It is a block diagram which shows the fuel cell system shown in FIG. It is a flowchart of the control program performed with the control apparatus shown in FIG. It is a time chart which shows operation | movement of embodiment of the fuel cell system by this invention. It is a time chart which shows operation | movement of embodiment of the fuel cell system which does not apply this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Burner, 22 ... Reformer, 23 ... Carbon monoxide shift reaction part (CO shift part), 24 ... Carbon monoxide Selective oxidation reaction section (CO selective oxidation section), 25 ... evaporator, 30 ... condenser, 31 ... reformer gas condenser, 32 ... anode off-gas condenser, 33 ... cathode off-gas condenser, 34 ... combustion gas Condenser, 40 ... pure water device, 45 ... inverter, 46, 47 ... power line, 50 ... water reservoir, 53 ... reforming water pump, 61-66 ... piping, 68 ... reforming water supply pipe, 71 ... No. DESCRIPTION OF SYMBOLS 1 heat exchanger, 72 ... Heat-medium circulation circuit, 73 ... 1st pump, 74 ... Hot water tank, 75 ... Hot water circulation circuit, 76 ... 2nd pump, 78 ... Heater, 82 ... 2nd heat exchanger, 83 ... Condensation Heater circulation circuit, 84 ... third pump, 85 ... temperature sensor, 90 ... Control device.

Claims (3)

A fuel cell in which fuel is supplied to the fuel electrode, oxidant gas is supplied to the oxidant electrode, and electricity is generated by their chemical reaction;
A hot water tank for storing hot water,
A fuel cell system comprising a power supply line for supplying the power generation output of the fuel cell;
Heating means for raising the temperature of the fuel cell;
Power generation output detecting means for detecting the power generation output of the fuel cell;
User power consumption detecting means for detecting user power consumed by the power line;
When starting the fuel cell system, the fuel cell system is heated using the hot water in the hot water storage tank until the power that exceeds the user power consumption can be supplied, and the power generation output is controlled. And control means for controlling to supply to the heating means the power that exceeds the user power consumption out of the power generation output if it is possible to supply the power that exceeds the user power consumption.
Fuel cell temperature detecting means for detecting the temperature of the fuel cell,
The control means includes
First power generation control means for controlling the power generation output of the fuel cell so that the power generation of the fuel cell is started and a predetermined power generation amount is obtained when a predetermined condition is satisfied;
Determining means for determining whether or not the power generation output exceeds user power consumption;
Energization start means for starting energization of the heating means when it is determined by the determination means that the power generation output exceeds user power consumption;
When the temperature of the fuel cell detected by the fuel cell temperature detecting means reaches 60 ° C. or higher, the power supply stopping means for stopping the current supply to the heating means at that time, and the user power consumption after the time point And a second power generation control means for controlling the power generation output of the fuel cell to follow the fuel cell system. The heat medium circulation circuit according to claim 1, wherein a heat medium that exchanges heat with the fuel cell circulates, and the heat medium exchanges heat with the hot water in the hot water storage tank using a heat exchanger .
A circulation means provided on the heat medium circulation circuit for circulating the heat medium;
The fuel cell system according to claim 1, wherein the heating means is a heat medium heating means provided on the heat medium circulation circuit and energized to raise the temperature of the heat medium.   3. The fuel cell system according to claim 1, wherein a heat medium temperature detecting means for detecting a temperature of the heat medium is adopted as the fuel cell temperature detecting means.

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