JP4087840B2 - 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.

  As one type of such a fuel cell system, one shown in Patent Document 1 “Fuel Cell Power Generation Device” is known. As shown in FIG. 1 of Patent Document 1, the fuel cell system includes a fuel cell 1 that generates power with fuel and an oxidant, a heater 7 that raises the temperature of the fuel cell 1, and a power generation start of the fuel cell 1. And a controller 10 for stopping the heater 7 at the start of power generation of the fuel cell 1 while making the power at the time a power that generates substantially the same amount of heat as that generated by the heater 7 immediately before the start of the power generation. . When the fuel cell power generator is activated (001), the controller 10 operates the cooling water pump 5 (002), and then operates the heater 7 with the heat output of the heater 7 set to the maximum (003). The temperature of the fuel cell 1 is increased by feeding the cooled water to the fuel cell 1. Then, the thermal output W of the heater 7 is adjusted so that the temperature T of the fuel cell 1 detected by the temperature detector 8 becomes the target temperature Tr (70 ° C.) (004). After the absolute value of the difference between the temperature T of the fuel cell 1 and the target temperature Tr (70 ° C.) becomes 1 ° C. or less (005), the heat output W of the heater 7 and the maximum heat amount Q generated by the fuel cell 1 during power generation (006), only temperature control is continued without starting power generation until the thermal output W of the heater 7 becomes equal to or less than the maximum heat quantity Q generated by the fuel cell 1. When the heat output W of the heater 7 becomes equal to or less than the maximum heat quantity Q of the fuel cell 1, the heater 7 is stopped and power generation of the fuel cell 1 is started (007).

  Further, as another format, one disclosed in Patent Document 2 “Fuel Cell Cogeneration System” is known. As shown in FIG. 1 of Patent Document 2, the fuel cell cogeneration system recovers heat by using off-gas combustor 5 for burning anode off-gas of fuel cell stack 4 and off-gas combustion heat 5 as hot water. For this purpose, a heat exchanger 6 installed on the downstream side of the stack cooling water and a three-way switching valve 9 for switching the supply destination of the reformed gas from the reformer according to the operating state of the system and the demand for hot water are provided. Accordingly, the off-gas energy is optimally used to eliminate the need for warming up the battery by the heater, suppress energy loss, and eliminate the need for a storage tank, thereby preventing an increase in size and cost of the apparatus.

Further, as another type, one disclosed in Patent Document 3 “Fuel Cell System” is known. As shown in FIG. 1 of Patent Document 3, the fuel cell system includes a fuel cell 2 that generates power using fuel gas and an oxidant gas, and combustion means 3 that combusts the fuel gas off-gas of the fuel cell 2. In the fuel cell system, heat exchange means 51 and 52 are provided between the exhaust gas discharged from the combustion means 3 and at least one of the fuel gas and the oxidant gas supplied to the fuel cell 2. Thus, the fuel gas and oxidant gas supplied to the fuel cell are controlled to the necessary temperatures, and water vapor is not condensed, and a highly efficient fuel cell system having excellent power generation performance is provided.
JP 2003-45465 A (page 2-4, FIG. 1-3) JP 2002-289227 A (page 4-6, FIG. 1-5) JP 2000-223138 A (page 4-7, FIG. 1-5)

  In the fuel cell power generation device described in Patent Document 1 described above, since the fuel cell 1 is warmed up by the heat of the heater 7 from the start of the fuel cell power generation device to the start of power generation, the power for operating the heater 7 There is a problem that the system efficiency deteriorates. In the fuel cell cogeneration system described in Patent Document 2 described above, the fuel cell is warmed up by making the device compact and optimally utilizing off-gas energy. However, since the storage tank is not provided, the fuel cell is not exhausted. There was a problem that the system efficiency deteriorated as a whole because heat was not efficiently recovered.

  The present invention has been made to solve the above-described problems. When starting a fuel cell system, a fuel capable of achieving both early warm-up of the fuel cell and improvement of system efficiency without causing flooding. An object is to provide a battery system.

In order to solve the above problems, the structural feature of the invention according to claim 1 is that a fuel cell and an oxidant gas are supplied to the fuel electrode and the oxidant electrode, respectively, and a fuel cell that generates electric power by their chemical reaction, and a fuel A reformer that generates gas and supplies it to the fuel electrode, a fuel cell heat medium circulation circuit that circulates a fuel cell heat medium that exchanges heat with the fuel cell, and a first heat medium that recovers exhaust heat from the reformer A fuel cell system comprising: a circulating first heat medium circulation circuit; a heat exchange means for exchanging heat between the fuel cell heat medium and the first heat medium; and a heating means for heating the fuel cell. Control means for controlling the operation of the system further comprising: first heating control means for starting heating of the fuel cell by the first heat medium via the heat exchange means from the start of starting the fuel cell system ; start the power generation of the fuel cell Determination means for determining whether it is necessary to heat by the heating means in the previous time to, the heating was terminated by the first heat medium, if it is determined that determine the constant means is necessary to heat by the heating means, And a second heating control means for starting heating of the fuel cell by the heating means .

Further, the constitutional feature of the invention according to claim 2 is that a fuel cell and an oxidant gas are supplied to the fuel electrode and the oxidant electrode, respectively, and a fuel cell that generates electric power by their chemical reaction; A reformer supplied to the fuel cell, a fuel cell heat medium circulation circuit in which a fuel cell heat medium that exchanges heat with the fuel cell circulates, and a first heat medium circulation in which a first heat medium that collects the exhaust heat of the reformer circulates A circuit, a hot water circulation circuit in which hot water stored in the hot water tank circulates, a first heat exchanger in which heat is exchanged between the hot water and the fuel cell heat medium, hot water and the first heat medium A heat exchange between the fuel cell heat medium and the first heat medium, the second heat exchanger performing heat exchange between the fuel cell heat medium and the hot water circulation means provided in the hot water circulation circuit for circulating the hot water. Fuel provided with exchange means and heating means for heating the fuel cell The battery system further comprises control means for controlling the operation of the fuel cell system, and the control means starts heating the fuel cell with the first heat medium via the heat exchange means from the start of the start of the fuel cell system. First heating control means for determining, determining means for determining whether heating by the heating means is necessary before the time point at which power generation of the fuel cell is started, and determining that the determining means requires heating by the heating means In this case, a second heating control means for starting heating of the fuel cell by the heating means is provided .
Further, the structural feature of the invention according to claim 3 is that, in claim 2, a bypass path for bypassing the hot water tank is provided in the hot water circulation circuit, and the hot water tank bypasses the hot water tank and flows through the bypass path. The first heat exchanger and the second heat exchanger are provided on the flow path through which the hot water is flowing.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the first heating control means is means for heating the fuel cell when the reformer is warmed up. That is.
Further, the structural feature of the invention according to claim 5 is that, in any one of claims 1 to 4, the determination means performs determination when the warm-up of the reformer is completed. .
Further, the structural feature of the invention according to claim 6 is that, in any one of claims 1 to 4 , the judging means completes warming up of the reformer, and the temperature of the fuel cell heat medium is the first. 1 Heating by the heating means is performed before the time when the temperature of the fuel cell heating medium becomes higher than a temperature higher by a predetermined temperature difference from the inlet temperature of the fuel electrode of the fuel gas and the power generation of the fuel cell is started. It is to determine whether it is necessary.

Further, the structural feature of the invention according to claim 7 is that, in any one of claims 1 to 6 , the heat exchange means can further prohibit heat exchange between the fuel cell heat medium and the first heat medium. The heat exchanging means prohibits heat exchange when the judging means judges that heating by the heating means is necessary.

A structural feature of the invention according to claim 8 is that, in any one of claims 1 to 6 , the first heat medium circulation means for circulating the first heat medium in the first heat medium circulation circuit; A cooling means for cooling the first heat medium; and a condenser for recovering heat from the fuel gas supplied from the reformer and before flowing into the fuel electrode of the fuel cell to condense the gas, When the means determines that heating by the heating means is necessary, the control means controls the first heat medium to a flow rate suitable for cooling by the first heat medium circulation means and cools the first heat medium by the cooling means. Is to start.

In the invention according to claim 1 configured as described above, the first heating control means starts heating the fuel cell with the first heat medium via the heat exchange means from the start of the start of the fuel cell system, determination means determines whether it is necessary to heat by the heating means in a previous time to start power generation of the fuel cell, the second heating control means ends the heating by the first heat medium, the determination unit When it is determined that heating by the heating unit is necessary, heating of the fuel cell by the heating unit is started. According to this, from the start of the start of the fuel cell system, the fuel cell is warmed up via the first heat medium and the fuel cell heat medium using the exhaust heat of the reformer. Is the temperature of the first heat medium> the temperature of the fuel cell heat medium (fuel cell), that is, the temperature of the fuel gas supplied to the fuel electrode of the fuel cell> the temperature of the fuel cell heat medium (fuel cell). If the temperature relationship is as it is, the fuel gas is flooded at the fuel electrode. On the other hand, since the fuel cell is heated by the heating means as necessary, the temperature of the fuel cell rises, and the temperature of the fuel gas supplied to the fuel electrode becomes less than the temperature of the fuel cell (fuel cell heat medium). In this case, flooding can be prevented. Therefore, in order to warm up the fuel cell when the fuel cell system is started up, the heat from the reformer is basically used, while the heating means is used as necessary from the viewpoint of preventing flooding. As a result, it is possible to improve the controllability of the startup control, suppress the warm-up of the fuel cell by the heating means to the minimum necessary, and reduce the energy required for startup.
Furthermore, when the heating by the first heat medium is finished and the determination unit determines that the heating by the heating unit is necessary, the second heating control unit starts heating the fuel cell by the heating unit. Thereby, after switching to the heating means, the fuel cell is heated only by the heating means, and heating by the first heat medium (circulation of the first heat medium) is not performed. It is possible to reliably prevent the heat generated in the heat medium) from being carried away through the first heat medium.

In the invention according to claim 2 configured as described above, the first heating control means starts heating the fuel cell with the first heat medium via the heat exchange means from the start of the start of the fuel cell system, The determination means determines whether or not heating by the heating means is necessary before the time when the fuel cell power generation is started, and the second heating control means determines that the determination means needs heating by the heating means In the case, heating of the fuel cell by the heating means is started. According to this, from the start of the start of the fuel cell system, the fuel cell is warmed up via the first heat medium and the fuel cell heat medium using the exhaust heat of the reformer. Is the temperature of the first heat medium> the temperature of the fuel cell heat medium (fuel cell), that is, the temperature of the fuel gas supplied to the fuel electrode of the fuel cell> the temperature of the fuel cell heat medium (fuel cell). If the temperature relationship is as it is, the fuel gas is flooded at the fuel electrode. On the other hand, since the fuel cell is heated by the heating means as necessary, the temperature of the fuel cell rises, and the temperature of the fuel gas supplied to the fuel electrode becomes less than the temperature of the fuel cell (fuel cell heat medium). In this case, flooding can be prevented. Therefore, in order to warm up the fuel cell when the fuel cell system is started up, the heat from the reformer is basically used, while the heating means is used as necessary from the viewpoint of preventing flooding. As a result, it is possible to improve the controllability of the startup control, suppress the warm-up of the fuel cell by the heating means to the minimum necessary, and reduce the energy required for startup.
Further, the heat exchange means includes a hot water circulation circuit in which hot water stored in the hot water tank circulates, a first heat exchanger in which heat is exchanged between the hot water and the fuel cell heat medium, Since it is composed of a second heat exchanger that exchanges heat with one heat medium, and a hot water circulating means that circulates the hot water and is provided in the hot water circulating circuit, the existing configuration is used accurately. Heat exchange between the fuel cell heat medium and the first heat medium can be performed.
In the invention which concerns on Claim 3 comprised as mentioned above, in the invention which concerns on Claim 2, the bypass path which bypasses a hot water tank is provided in the hot water circulation circuit, Hot water storage water which bypasses a hot water tank and flows through a bypass path Since the first heat exchanger and the second heat exchanger are provided on the flow path through which the hot water flows, when the temperature of the hot water is low, the heat from the first heat medium is recovered and returned to the hot water tank. The hot water can be heated (temperature rise), and when the temperature of the hot water is high, the hot water is not returned to the hot water tank, so that the temperature layer collapse of the hot water tank can be prevented.

In the invention according to Claim 5 configured as described above, in any one of Claims 1 to 4, the determination means performs determination when the warming-up of the reformer is completed. It is possible to determine whether or not the heating by the heating means is necessary with the maximum utilization of the exhaust heat from the reformer.
In the invention according to claim 6 configured as described above, in any one of claims 1 to 4 , the determination means completes warming up of the reformer, and the temperature of the fuel cell heat medium is Heating by the heating means before the time when the fuel cell heating medium becomes higher than the first predetermined temperature and the temperature of the fuel cell heating medium is higher than the temperature higher than the inlet temperature of the fuel electrode fuel electrode by a predetermined temperature difference to start power generation of the fuel cell. It is determined whether or not is necessary. As a result, generation of flooding is reliably suppressed at the fuel electrode and the oxidant electrode, and power generation is started, so that high power generation efficiency is achieved.

In the invention according to Claim 7 configured as described above, in the invention according to any one of Claims 1 to 6 , the heat exchange means further includes heat generated between the fuel cell heat medium and the first heat medium. Since the heat exchange means prohibits heat exchange when the determination means determines that heating by the heating means is necessary, the heat energy of the heating means is conducted to the first heat medium. Instead, the fuel cell is used only for heating the fuel cell to effectively use the heat energy of the heating means and warm up the fuel cell early.

In the invention according to Claim 8 configured as described above, in any one of Claims 1 to 6 , the first heat medium circulation means for circulating the first heat medium in the first heat medium circulation circuit. And a cooling means for cooling the first heat medium, and a condenser for recovering the amount of heat from the fuel gas supplied from the reformer and flowing into the fuel electrode of the fuel cell and condensing the gas, When the determination means determines that heating by the heating means is necessary, the control means controls the first heat medium to a flow rate suitable for cooling by the first heat medium circulation means and the first heat medium by the cooling means. Since the cooling is started, the temperature of the fuel gas is lowered at an early stage to lower the temperature by a predetermined temperature difference from the temperature of the fuel cell heat medium, and the start-up time is shortened by satisfying the power generation start condition at an early stage.

  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 (fuel 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 shift unit 23 includes a CO shift unit temperature sensor 23 a that detects an internal temperature, and the CO shift unit temperature sensor 23 a sends a detection result to the control device 90.

  The CO selective oxidation unit 24 generates carbon dioxide by reacting carbon monoxide remaining in the reformed gas and CO oxidation air (air) further supplied from the outside with a catalyst filled therein. is doing. 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. A reforming water pump 53 is provided in the reforming water supply pipe 68. 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 (although separated in the drawing) is integrally connected with a reforming gas condenser 31, an anode offgas condenser 32, a cathode offgas condenser 33, and a combustion gas condenser. It is a monolithic structure. 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 pipe 64 is provided with a fourth temperature sensor 64a in the vicinity of the inlet of the fuel electrode 11 of the fuel cell 10, and the fourth temperature sensor 64a is connected to the inlet of the fuel electrode 11 of the reformed gas fuel cell 10. The temperature T4 is detected, and the detection result is output to the control device 90. The pipe 64 is provided with a bypass path 67 that bypasses the fuel cell 10, and the bypass path 67 is provided with a valve 67 a that opens and closes the bypass path 67. A valve 64b that opens and closes the pipe 64 is provided between the bypass branch point of the pipe 64 and the inlet of the fuel electrode 11 of the fuel cell 10, and the bypass junction of the pipe 64 from the outlet of the fuel electrode 11 of the fuel cell 10 is provided. In the meantime, a valve 64c for opening and closing the pipe 64 is provided. These valves 67a, 64b, and 64c are controlled to open and close by a command from the control device 90, and when the concentration of carbon monoxide in the reformed gas supplied from the reformer 20 is high when the fuel cell 10 is started. In order to avoid poisoning of the fuel electrode 11, the valve 67a is opened, the valves 64b and 64c are closed, and the reformed gas is supplied directly to the burner 21 without passing through the fuel cell 10, so that the carbon monoxide concentration in the reformed gas is increased. When it is lowered, the valve 67a is closed and the valves 64b and 64c are opened to supply the fuel cell 10.

  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 hot water tank 71 for storing hot water, a hot water circulation circuit 72 for circulating the hot water, and a fuel cell heat medium circulation for circulating FC cooling water as a fuel cell heat medium for exchanging heat with the fuel cell 10. FC cooling water circulation circuit 73 which is a circuit, a first heat exchanger 74 in which heat is exchanged between hot water and FC cooling water, and first heat which is recovered from exhaust heat from the reformer 20 and the FC cathode offgas. A second heat exchanger 76 in which heat is exchanged between the hot water and the condensed refrigerant, and a condensed refrigerant circuit 75 that is a first heat medium circuit in which condensed refrigerant (condenser heat medium) that is a heat medium circulates. And are provided. In the present specification and the accompanying drawings, “FC” is described as an abbreviation for “fuel cell”.

  Thereby, the exhaust heat (thermal energy) generated in the reformer 20 is recovered by the condensed refrigerant through the condenser 30 to raise the temperature of the condensed refrigerant, and the second condition is that the condensed refrigerant is at a higher temperature than the stored hot water. Heat is recovered in the hot water via the heat exchanger 76, and as a result, the hot water is heated (heated up). Heat is transferred from the heated hot water to the FC cooling water via the first heat exchanger 74 (at the time of startup).

  At the time of FC power generation, the exhaust heat (thermal energy) generated in the fuel cell 10 is recovered in the FC cooling water to raise the temperature of the FC cooling water, and if the FC cooling water is higher than the hot water, the first heat exchanger Heat is transferred from the FC cooling water to the stored hot water via 74 to heat (heat up) the stored hot water, and the thermal energy of the fuel cell 10 is used as hot water. On the contrary, if the hot water is higher than the FC cooling water, the heat of the hot water is recovered to the FC cooling water via the first heat exchanger 74, and as a result, the FC cooling water is heated (temperature rise).

  The hot water storage tank 71 is provided with one columnar container, in which hot water is stored in a layered manner, that is, the temperature of the upper part is the highest and lower as it goes to the lower part, and the temperature of the lower part is the lowest. It has become so. Water (low-temperature water) such as tap water is replenished to the lower part of the columnar container of the hot water tank 71, and hot hot water stored in the hot water tank 71 is led out from the upper part of the columnar container of the hot water tank 71. ing. The hot water storage tank 71 is of a sealed type, and the pressure of tap water is directly applied to the inside, and consequently to the hot water storage water circulation circuit 72.

  One end and the other end of the hot water circulating circuit 72 are connected to the lower part and the upper part of the hot water tank 71. On the hot water circulation circuit 72, a hot water circulation pump P1, a second heat exchanger 76, a first heat exchanger 74, and a second valve 72a (described later), which are hot water circulation means, are arranged in order from one end to the other end. Has been. The hot water storage water circulation pump P1 sucks hot water stored in the lower part of the hot water storage tank 71, passes the hot water storage circuit 72 through the hot water storage circuit 71, and discharges it to the upper part of the hot water storage tank 71. ) Is controlled.

  With this configuration, the FC cooling water and the condensed refrigerant exchange heat through the hot water. That is, the hot water circulating circuit 72, the first heat exchanger 74, the second heat exchanger 76, and the hot water circulating pump P1 constitute a heat exchanging means for exchanging heat between the fuel cell heat medium and the first heat medium. Can be implemented.

  The hot water storage circuit 72 is provided with a bypass 78 that bypasses the hot water tank 71. The bypass path 78 is provided with a first valve 78 a that controls opening and closing of the bypass path 78 according to a command from the control device 90. The stored hot water circulation circuit 72 between the branching source of the bypass passage 78 and the hot water storage tank 71 is provided with a second valve 72 a for controlling the hot water storage water circulation circuit 72 to open and close according to a command from the controller 90. When the first and second valves 78 a and 72 a are closed and opened, the hot water flows into the hot water tank 71.

  On the other hand, when the hot water circulating pump P1 is operated with the first and second valves 78a and 72a opened and closed, the hot water does not flow into the hot water tank 71 but passes through the bypass passage 78, and the first and second heat exchangers 74, The hot water circulating circuit 72 is circulated through 76. As a result, it is possible to suppress the temperature layer collapse of the hot water tank 71 caused by returning the relatively low temperature hot water after heat exchange from the first heat medium to the FC cooling water to the hot water tank 71, and to warm the FC. The machine can be performed efficiently. In addition, since the hot water circulating pump P1 is stopped, heat exchange between the fuel cell heat medium and the first heat medium can be prohibited, so that the heat exchange means can be prohibited from heat exchange with a simple configuration. Can do. The heat exchange means may be of a type that directly exchanges heat through a heat exchanger between the fuel cell heat medium and the first heat medium.

  An FC cooling water circulation pump P3, which is an FC cooling water circulation means, is disposed on the FC cooling water circulation circuit 73. This FC cooling water circulation pump P3 is controlled by the control device 90 to control its flow rate (delivery amount). It has come to be. Further, on the FC cooling water circulation circuit 73, first and second temperature sensors 73a and 73b are disposed, and the first and second temperature sensors 73a and 73b are respectively provided at the inlet of the fuel cell 10 for FC cooling water. The temperature and the outlet temperature are detected, and the detection results are output to the control device 90. Further, a first heat exchanger 74 is disposed on the FC cooling water circulation circuit 73.

  In addition, a heater 79 (electric heater), which is a fuel cell heating medium heating unit that is energized to raise the temperature of the fuel cell heating medium, is provided on the FC cooling water circulation circuit 73. The heater 79 is controlled to be energized / de-energized or to control the amount of heat generated by a command from the control device 90. When the heater 79 is energized and turned on and the FC cooling water circulation pump P3 is driven, the high-temperature FC cooling water heated by the heater 79 is supplied to the fuel cell 10 to raise the temperature of the fuel cell 10. Therefore, the heater 79 is a heating means for heating the fuel cell 10. Further, the amount of heat supplied to the fuel cell 10 by the heating means is preferably larger than the amount of heat from the condensed refrigerant supplied via the heat exchange means described above. As a result, the amount of heat larger than the amount of heat from the condensed refrigerant can be supplied to the fuel cell 10 to warm up, so the warm-up time can be shortened compared to the case of heating with the heat of the condensed refrigerant. As a heating means, a type that directly heats the fuel cell 10 (for example, an electric heating member that is built in the fuel cell 10 or disposed outside, or a configuration that directly blows hot air) may be employed.

  A condensed refrigerant circulation pump P2 which is a condensed refrigerant circulation means is disposed on the condensed refrigerant circulation circuit 75, and this condensed refrigerant circulation pump P2 is controlled by the control device 90 to control its flow rate (delivery amount). It has come to be. On the condensing refrigerant circulation circuit 75, an anode off-gas condenser 32, a combustion gas condenser 34, a cathode off-gas condenser 33, and a reformed gas condenser 31 are arranged in order from the upstream. A third temperature sensor 75a is disposed on the condensed refrigerant circulation circuit 75, and the third temperature sensor 75a detects the outlet temperature of the condensed refrigerant reformed gas condenser 31, and the detection result thereof. Is output to the control device 90. Further, a second heat exchanger 76 is disposed on the condensed refrigerant circulation circuit 75. In addition, arrangement | positioning of each condenser 31-34 is not restricted to the order mentioned above, Moreover, each condenser 31-34 is not restricted to the case where it arrange | positions in series with one piping, and branches the condensed refrigerant | coolant circulation circuit 75 into plurality. And you may make it arrange | position in parallel at each branch path.

  The condensed refrigerant circulation circuit 75 is provided with a radiator 77 that is a cooling means for cooling the condensed refrigerant immediately downstream of the second heat exchanger 76. The radiator 77 is ON / OFF controlled by a command from the control device 90. The radiator 77 cools the condensed refrigerant when in the on state and does not cool when in the off state.

  Moreover, each temperature sensor 73a, 73b, 75a, 64a mentioned above, each pump P1-P3, 53, the radiator 77, and the heater 79 are connected to the control apparatus 90 (refer 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 controls the overall operation of the fuel cell system, and executes a program corresponding to the flowchart of FIG. 3 so that the fuel cell 10 can quickly generate power when the fuel cell system is activated. Control of each pump P1-P3, the radiator 77, and the heater 79 is performed. 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. FIG. 3 is a flowchart of a control program executed by the control device 90, and FIGS. 4 and 5 are time charts showing operations when one embodiment of the fuel cell system is used in winter and summer, respectively. 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 (time t0, t10). That is, 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 supplied to the fuel cell 10 because the reformed gas composition (H ₂ concentration, CO concentration) does not satisfy the conditions necessary for the fuel cell 10. Absent.

  When the fuel cell system is activated, the process of step 104 is executed and the exhaust heat of the reformer 20 (reformed gas) is used until the warm-up of the reformer 20 is completed (time t1, t11). Then, the fuel cell 10 is warmed up. The processing in step 104 will be described for each circulation circuit. In the hot water circulating circuit 72, the first and second valves 78a and 72a are opened and closed, respectively, and the hot water does not flow through the hot water circulating circuit 72 and the bypass 78 and flow into the hot water tank 71. This prevents the low temperature hot water from flowing in from the upper part of the hot water tank 71 and causing the temperature layer to collapse. In addition, the hot water circulation pump P1 is controlled to have a prescribed flow rate. This specified flow rate is set so that the outlet temperature of the second heat exchanger 76 of the hot water becomes a high specified temperature.

  In the condensing refrigerant circulation circuit 75, each condenser 31 to 34 has a high-temperature reformed gas, a reformed gas that bypasses the fuel cell 10 (until power generation starts, anode off-gas after power generation starts), cathode off-gas, The combustion gas is circulated, and heat exchange is performed between the gas and the condensed refrigerant, and the condensed refrigerant recovers the exhaust heat of the reformer 20 and is heated. The condensed refrigerant circulation pump P2 has an inlet temperature T4 of the reformed gas fuel cell 10 detected by the fourth temperature sensor 64a (or an outlet of the condensed refrigerant reformed gas 31 detected by the third temperature sensor 75a). The flow rate is controlled so that the temperature T3) becomes the target temperature T4-x (or T3-x). Further, since the radiator 77 is in an off state and is not exhausted from the radiator 77, most of the heat recovered by the condensed refrigerant is recovered in the hot water storage via the second heat exchanger 76.

  In the FC cooling water circulation circuit 73, the flow rate of the FC cooling water pump P3 is controlled so as to become a specified flow rate. This specified flow rate is set so that heat can be efficiently recovered from the hot water storage to the FC cooling water.

  Therefore, as shown in the first stage of FIGS. 4 and 5, the reformed gas fuel cell inlet temperature T4 is maintained at T4-x. Further, the condensed refrigerant circulating in the condensed refrigerant circulation circuit 75 that has recovered the exhaust heat of the reformer 20 is the second heat exchanger 76 constituting the heat exchange means, the hot water stored in the hot water circulating circuit 72 and the first heat. The fuel cell 10 is heated via the exchanger 74 and the FC cooling water circulating in the FC cooling water circulation circuit 73. At this time, as shown in the first stage of FIGS. 4 and 5, the FC cooling water temperature (that is, the FC cooling water FC outlet temperature T2) is raised. Thus, by the process of step 104, heating of the fuel cell 10 by the first heat medium is started via the heat exchange means from the start of the start of the fuel cell system (first heating control means). 4 and 5, in order from the top, the first stage indicating the reformed gas fuel cell inlet temperature T4 and the FC cooling water temperature T2, the second stage indicating the control of the hot water circulation circuit system, and the condensed refrigerant circulation circuit. The third stage showing the control of the system and the fourth stage showing the control of the heater 79 are described.

  In step 106, the controller 90 determines whether or not the warming up of the reformer 20 has been completed. If the warming up has been completed, the control device 90 advances the program to step 108 and thereafter. In the determination of the completion of warm-up, if the temperature in a predetermined portion of the reformer 20, for example, the temperature in the CO shift unit 23 has reached the warm-up completion determination temperature, it is determined that the process is complete. The warm-up completion determination temperature is defined as a temperature at which the carbon monoxide concentration becomes a predetermined specified value within the activation temperature region of the catalyst of the CO shift unit 23. Therefore, if the warm-up is completed, it is determined that the amount of hydrogen and the concentration of carbon monoxide in the reformed gas derived from the reformer 20 have reached specified values.

  In the processing of steps 108 to 116, the control device 90 switches the heating source of the fuel cell 10 from the condensed refrigerant recovery heat to the heater 79 and heats the fuel cell 10 (time t1, t11). Specifically, in step 108, the hot water circulating pump P1 is stopped, so that the hot water is not circulated in the hot water circulating circuit 72. As a result, the hot water that has recovered heat from the condensed refrigerant in the second heat exchanger 76 does not reach the first heat exchanger 74, so the heat exchange means stops heat exchange between the condensed refrigerant and the FC cooling water.

  With the control described below, the temperature of the condensed refrigerant decreases, and accordingly, the temperature of the hot water stored on the downstream side of the second heat exchanger 76 also decreases. Therefore, by stopping the heat exchange between the condensed refrigerant and the FC cooling water via the hot water, the heat from the heater 79 is prevented from moving to the hot water. Thereby, FC can be warmed up efficiently.

  In the condensed refrigerant circulation circuit 75, as described above, the condensed refrigerant is heated by collecting the exhaust heat of the reformer 20. In step 108, the radiator 77 is turned on. The flow rate of the condensing refrigerant circulation pump P2 is controlled to be a specified flow rate. This specified flow rate is set to a large flow rate in order to efficiently cool the reformed gas FC inlet temperature T4, that is, the condensed refrigerant reformed gas condenser outlet temperature T3, with the radiator 77 in the on state. As a result, the reformed gas FC inlet temperature T4, that is, the condensed refrigerant reformed gas condenser outlet temperature T3, is rapidly lowered and thereafter becomes a constant temperature. As a result, the reformed gas FC inlet temperature T4 can be made lower than the FC cooling water temperature T2 in a short time, and thus early warm-up can be achieved. Note that the constant temperature is affected by the outside air temperature, and the winter temperature when the outside air temperature is low is lower than the summer time when the outside air temperature is high (see FIGS. 4 and 5).

  In step 110, the controller 90 determines whether or not the FC coolant temperature T2 is higher than the first predetermined temperature T2-a. At the time when the reformer warm-up is completed (time t1, t11), since the FC cooling water is not sufficiently heated, it is equal to or lower than the first predetermined temperature T2-a. In step 112, the heater 79 is turned on. The amount of heat supplied to the fuel cell 10 by the heater 79 is greater than the amount of heat from the condensed refrigerant supplied via the heat exchange means described above. Further, in the FC cooling water circulation circuit 73, the flow rate of the FC cooling water pump P3 is controlled so as to become the specified flow rate as described above. Therefore, when the heating by the heater 79 is started, the rate of temperature increase of the FC cooling water temperature T2 becomes larger than the heating by the condensed refrigerant.

  Thus, the FC cooling water temperature T2 is raised by the heater 79 and becomes higher than the first predetermined temperature T2-a (determined as “YES” in Step 110), and from the reformed gas fuel cell inlet temperature T4. When the temperature is higher than the temperature higher by the predetermined temperature difference ΔT−a (determined as “YES” in step 114), control device 90 starts power generation of fuel cell 10 in step 118 (time t3, t13). This power generation start condition is that the warm-up of the reformer 10 is completed, the FC cooling water temperature T2 is higher than the first predetermined temperature T2-a, and the reformed gas fuel electrode 11 inlet temperature T4 is predetermined. The temperature difference is higher than the higher temperature by ΔT−a. In step 114, it is determined whether or not a subtracted value ΔT obtained by subtracting the FC coolant temperature T2 from the fuel cell inlet temperature T4 is greater than a first predetermined temperature T2-a. The first predetermined temperature T2-a is set to a value at which no flooding occurs at the oxidant electrode 12 of the fuel cell 10, and the predetermined temperature difference ΔT-a occurs at the fuel electrode 11 of the fuel cell 10. There is no value set. Further, in step 116, it is determined whether or not the reformed gas stabilization wait time has elapsed since the completion of the reformer warm-up.

  Steps 110 and 114 described above are determination means, which are determined before the time when the fuel cell power generation start condition is satisfied (that is, the power generation start time) and when the warm-up of the reformer 20 is completed. It is then determined whether heating by the heater 79 is necessary. When it is determined that heating by the heater 79 is necessary, the control device 90 ends the heating by the first heating means at the time of the determination, and starts the heating of the fuel cell 10 by the heater 79 (second heating). Control means).

  When the control device 90 starts power generation in step 118 (time t3, t13), the fuel cell 10 is heated by heat generated by power generation. Therefore, the heater 79 is turned off to save energy (step 120). Then, until the temperature T2 of the FC cooling water becomes higher than the steady operation temperature T2-b (time t4, 14), the flow rate of the condensing refrigerant circulation pump P2 is controlled to become the specified flow rate (step 120).

  When the temperature T2 of the FC cooling water reaches the steady operation temperature T2-b (time t4, 14), the control device 90 drives the hot water circulating pump P1 so that the temperature T2 of the FC cooling water is the steady operation temperature T2. The flow rate is controlled so as to be −b. The control device 90 controls the flow rate of the FC cooling water circulation pump P3 so that the difference between the fuel cell inlet temperature T1 and the outlet temperature T2 of the FC cooling water becomes a predetermined temperature difference. Further, the condensing refrigerant circulation pump P2 controls the flow rate so that the reformed gas FC inlet temperature T4 becomes the anode optimum humidification condition T4-b. Further, since the heat exchange between the condensed refrigerant and the hot water is resumed in the second heat exchanger 76, the radiator 77 is turned off so that the heat quantity of the condensed refrigerant that has been discarded is recovered in the hot water. In step 126, steady operation is performed.

  As is apparent from the above description, in this embodiment, the first heating control means (step 104) starts the fuel cell using the first heat medium via the heat exchange means from the start of the start of the fuel cell system. 10 is started, and the determination means (steps 110 and 114) determines whether or not heating by the heater 79 is necessary before the time point when the power generation start condition of the fuel cell 10 is satisfied, and the second heating control means (Step 112) starts heating the fuel cell 10 by the heater 79 when the determination means determines that heating by the heater 79 is necessary. According to this, the fuel cell 10 is warmed up via the first heat medium and the fuel cell heat medium using the exhaust heat of the reformer 20 from the start of the fuel cell system start-up. Until the start, the temperature of the first heat medium> the temperature of the fuel cell heat medium (fuel cell), that is, the temperature of the fuel gas supplied to the fuel electrode 11 of the fuel cell 10> the fuel cell heat medium (fuel cell). ), The reformed gas (fuel gas) is flooded at the fuel electrode 11. On the other hand, since the fuel cell 10 is heated by the heater 79 as necessary, the temperature of the fuel cell 10 rises, and the temperature of the fuel gas supplied to the fuel electrode 11 <the temperature of the fuel cell (fuel cell heat medium), Flooding can be prevented at the start of power generation. Therefore, in order to warm up the fuel cell 10 when the fuel cell system is started up, the exhaust heat of the reformer 20 is basically used, while the heater 79 is installed as necessary from the viewpoint of preventing flooding. By using this, it is possible to improve the controllability of the startup control, suppress the warm-up of the fuel cell 10 by the heater 79 to the minimum necessary, and reduce the energy required for startup.

  When the determination means (steps 110 and 114) determines that heating by the heater 79 is necessary, the second heating control means (step 112) ends the heating by the first heat medium, and the fuel by the heater 79 Heating of the battery 10 is started. Thus, after switching to the heater 79, the fuel cell 10 is heated only by the heater 79, and heating by the first heat medium (circulation of the first heat medium) is not performed. It is possible to reliably prevent the heat generated in the fuel cell heat medium) from being carried away through the first heat medium.

  The power generation start condition is that the warming-up of the reformer 20 is completed, the FC cooling water temperature T2 is higher than the first predetermined temperature T2-a, and the reformed gas fuel electrode inlet temperature T4 is set to the predetermined temperature. Since the temperature is higher than the temperature higher by the difference ΔT−a, the generation of flooding is surely suppressed at the fuel electrode 11 and the oxidant electrode 12, and power generation is started. Therefore, high power generation efficiency is achieved.

  The heat exchanging means is configured to prohibit heat exchange between the fuel cell heat medium and the first heat medium. When the determination means determines that heating by the heater 79 is necessary, the heat exchange means Since the heat exchange is prohibited, the heat energy of the heater 79 is used only for heating the fuel cell 10 without being lost through the stored hot water so that the heat energy of the heater 79 is effectively used and the fuel cell 10 is warmed up early. To work.

  Further, when the determination unit determines that heating by the heating unit is necessary, the condensed refrigerant circulation pump P2 controls the condensed refrigerant to a flow rate suitable for cooling (for example, increasing the condensed refrigerant to a predetermined flow rate). Since cooling of the condensed refrigerant by the radiator 77 is started, the reformed gas is cooled down at an early stage by the condenser 31 to a temperature lower by a predetermined temperature difference ΔT−a from the FC cooling water temperature T2, and the power generation start condition is satisfied at an early stage. To shorten the startup time.

  Moreover, since the determination means performs determination when the warm-up of the reformer 20 is completed, it can be determined whether or not heating by the heater 79 is necessary.

  Further, the completion of warming-up of the reformer 20 is determined when the temperature at a predetermined location of the reformer 20 is higher than the warm-up completion determination temperature, so that the exhaust heat from the reformer 20 is maximized. Completion of warm-up of the reformer 20 can be detected reliably and accurately after use.

  In addition, since the power generation of the fuel cell 10 is started after the reformed gas supplied from the reformer 20 is stabilized by the process of step 116, stable power generation can be performed.

  Further, when the power generation start condition of the fuel cell is satisfied, the heating of the fuel cell 10 by the heater 79 is stopped when the fuel cell generation start condition is satisfied, so that the heating by the heater 79 is stopped at an appropriate time and is not heated more than necessary. In this way, the warm-up time is shortened and the system efficiency is improved.

  Further, when the FC cooling water temperature T2 exceeds the steady operation temperature T2-b, the cooling of the condensed refrigerant by the radiator 77 is stopped and the heat exchange by the heat exchanging means is restarted when the temperature exceeds the normal operation temperature T2-b. The heat efficiency is improved by recovering the stored heat in the hot water storage.

  Further, since the heater 79 is a fuel cell heating medium heating unit that is provided on the FC cooling water circulation circuit 73 and energized to raise the temperature of the FC cooling water, the temperature adjustment of the fuel cell can be performed easily and accurately. it can.

  The heat exchanging means includes a hot water circulating circuit 72 in which hot water stored in the hot water tank 71 circulates, a first heat exchanger 74 in which heat is exchanged between the hot water and FC cooling water, and hot water. The second heat exchanger 76 that exchanges heat between the refrigerant and the condensed refrigerant and the hot water circulation pump P1 that is provided in the hot water circulation circuit 72 and circulates the hot water are used. Thus, heat exchange between the fuel cell heat medium and the first heat medium can be performed accurately.

  Further, a bypass passage 78 for bypassing the hot water tank 71 is provided in the hot water circulation circuit 72, and the hot water flowing through the bypass passage 78 bypassing the hot water tank 71 flows on the flow path (specifically, in the hot water circulation circuit 72. The first heat to the portion between the bypass branch point and the junction point, that is, from the hot water outlet of the hot water tank 71 to the bypass branch point, and from the bypass junction point to the hot water inlet of the hot water tank 71). Since the exchanger 74 and the second heat exchanger 76 are provided, when the temperature of the hot water is low, the heat from the first heat medium is recovered and returned to the hot water tank 71 to heat the hot water quickly. When the temperature of the hot water storage water is high, the hot water storage water is not returned to the hot water storage tank 71, and the temperature layer collapse of the hot water storage tank 71 can be prevented.

a) First Control Modification Example Next, a first control modification example in the above-described embodiment will be described with reference to FIGS. FIG. 6 is a flowchart of a control program of a first control modification executed by the control device 90, and FIGS. 7 and 8 illustrate operations when the embodiment of the fuel cell system is used in winter and summer, respectively. It is a time chart which shows. Note that the same reference numerals are assigned to the same (or substantially the same) structural members as those in the above-described embodiment, and the description thereof is omitted. Further, in the present specification and drawings, the first and second control modification examples are not related to the embodiment of the present invention but are reference examples.

  In the first control modification, it is determined whether or not heating by the heater 79 which is a heating unit is necessary before the reformer 20 is warmed up. This is different from the control described above in that it is heated. Instead of the above-described steps 106 and 116, the processing of steps 202 and 204 is executed.

  Specifically, in the above-described embodiment, if the predetermined location of the reformer 20, for example, the temperature in the CO shift unit 23 has reached the warm-up completion determination temperature in step 106, it is completed. At the time of determination, at step 110, it is determined whether or not heating by the heater 79 is necessary. In the first control modification example, at step 202, the reformer is determined. Whether or not heating by the heater 79 is necessary in step 110 at a time point (time t21, 31) when the temperature of the predetermined portion 20 becomes higher than the pre-warm-up completion determination temperature lower than the warm-up completion determination temperature. Is judged. Thereby, it can be reliably determined whether or not heating by the heater 79 is necessary. Further, the fuel is supplied by the heater 79 from a predetermined position of the reformer 20, for example, before the temperature in the CO shift unit 23 reaches the warm-up completion determination temperature, that is, before the warm-up of the reformer 20 is completed (time t22, t32). The battery 10 can be heated. Therefore, it is possible to further shorten the warm-up time by starting heating by the heating means earlier.

  Note that the determination temperature before the completion of warming-up is a temperature at which the warming-up of the reformer 20 is completed (for example, a warm-up completion determination temperature) from the processing effective time point (time t21, t31) of step 202 to the start of power generation (time t23, t33). (Temperature lower by 10 ° C.). Therefore, if the FC cooling water temperature T2 becomes higher than the first predetermined temperature T2-a and becomes higher than the temperature higher by the predetermined temperature difference ΔT-a from the inlet temperature T4 of the reformed gas fuel electrode, the controller 90 In steps 110, 114, and 204, “YES” is determined, and power generation is started in step 118. Step 204 is provided to confirm whether or not the reformer 20 has been warmed up.

b) Second Control Modification Next, a second control modification in the above-described embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a flowchart of the control program of the second control modification executed by the control device 90, and FIG. 10 is a time chart showing the operation of one embodiment of the fuel cell system. In addition, the same code | symbol is attached | subjected about the same component (or substantially the same) as the 1st control modification mentioned above, and the description is abbreviate | omitted.

  As in the first control modification described above, this second control modification determines whether or not heating by the heater 79, which is a heating means, is required before the reformer 20 is warmed up. Then, the fuel cell 10 is heated by the heater 79 from that time, but the completion of the reformer warm-up and the start of power generation are the same time based on the estimated FC cooling water temperature T2-tm1 and the estimated reformed gas FC inlet temperature T4-c. This is different from the above-described first control modification in that the heater 79 is turned on so that

  Specifically, the control device 90 is substantially the same as step 104 described above until the start of the start (time t40) and the predetermined portion (CO shift unit) of the reformer 20 exceeds the predicted control start temperature (time t41). The same processing in step 302 is repeated, the FC cooling water temperature T2 is increased by heat exchange with the condensed refrigerant, and the reformed gas FC inlet temperature T4 is maintained at T4-x (steps 302, 304, and 306). ). In step 302, processing for turning off the heater 79 is added to the processing in step 104 described above. In step 304, it is determined whether or not the flag F is 1. Since the flag F is 0 for the first time immediately after the start of activation, the program is advanced to step 306. In step 306, when the temperature at a predetermined location of the reformer 20 becomes higher than a temperature (for example, 100 ° C.) lower than the determination temperature before completion of warming-up (eg, time t41), heating by the heater 79 is performed in step 110. Is started (predictive control start determination means).

  When the predetermined location (CO shift unit 23) of the reformer 20 reaches the predicted control start temperature (time t41), the flag F is set to 1 (step 308), and the predetermined location of the reformer 20 detected up to the present time is detected. Based on the temperature data, a time at which the reformer 20 is warmed up (estimated warm-up completion time) is estimated (step 310: warm-up completion time estimation means), and the fuel cell heat medium temperature detected up to the present time ( Based on the data of the FC cooling water temperature and the heating capability of the heating means (heater 79), the temperature of the fuel cell heat medium at the warm-up completion time estimated by the warm-up completion time estimation means (estimated FC cooling water temperature T2- tm1) (step 312: fuel cell heat medium temperature estimation means), based on the data of the reformed gas fuel cell inlet temperature detected so far and the cooling capacity of the cooling means (radiator 77), The reformed gas fuel cell inlet temperature (estimated reformed gas FC inlet temperature T4-c) at the warm-up completion time estimated by the machine completion time estimating means is estimated (step 314: reformed gas fuel cell inlet temperature estimating means) ). Since the flag F has become 1, it is possible to execute the process of step 310 by determining “NO” in the next process of step 304 and skipping the process of step 306.

  Then, the controller 90 determines whether or not heating by the heater 79 is necessary based on the estimated FC cooling water temperature T2-tm1 estimated (calculated) and the estimated reformed gas FC inlet temperature T4-c as described above. Determine. That is, the estimated FC cooling water temperature T2-tm1 is higher than the first predetermined temperature T2-a, and a subtraction value obtained by subtracting the estimated reformed gas FC inlet temperature T4-c from the estimated FC cooling water temperature T2-tm1 is predetermined. If it is not satisfied that the temperature difference is higher than ΔT−a, it is determined that heating by the heater 79 is necessary, and if satisfied, it is determined that heating by the heater 79 is not necessary (step 316: determination means). This determination is made from the time (time t41) when the predetermined location (CO shift portion) of the reformer 20 exceeds the predicted control start temperature.

  For example, the estimated FC cooling water temperature T2-tm1 and the estimated reformed gas FC inlet temperature T4-c estimated at time t41 are values corresponding to the time t43 shown by the broken line in FIG. -Tm1 becomes higher than the first predetermined temperature T2-a, and a subtraction value obtained by subtracting the estimated reformed gas FC inlet temperature T4-c from the estimated FC cooling water temperature T2-tm1 becomes higher than the predetermined temperature difference ΔT-a. Therefore, it is determined that heating by the heater 79 is not necessary, the program is returned to step 302, and the FC cooling water temperature T2 is raised by heat exchange with the condensed refrigerant.

  Then, time elapses while the processes of Steps 302, 304, 310 to 316 are repeatedly executed, and in Step 316, the estimated FC cooling water temperature T2-tm1 becomes higher than the first predetermined temperature T2-a and is estimated. When the subtracted value obtained by subtracting the estimated reformed gas FC inlet temperature T4-c from the FC cooling water temperature T2-tm1 is not satisfied to be higher than the predetermined temperature difference ΔT-a (time t42), heating by the heater 79 is necessary. And the process of step 318 is executed. The process of step 318 is a combination of the turning on of the heater 79, which is the process of step 112 described above, and the processes of step 108. Accordingly, at the reformer warm-up completion time (time t43), the FC cooling water temperature T2 becomes higher than the first predetermined temperature T2-a, and the reformed gas FC inlet temperature T4 is subtracted from the FC cooling water temperature T2. Since the subtracted value becomes higher than the predetermined temperature difference ΔT−a, the heater 79 is turned on at time t42 so that the reformer warm-up completion and the power generation start are at the same time.

  According to this, since heating by the heater 79 is started in advance (at time t42) so that the power generation start condition is satisfied at the warm-up completion time (time t43), heating by the heater 79 is not performed more than necessary. In addition, it is possible to warm up the fuel cell 10 at an early stage without wasting energy and shorten the startup time of the fuel cell system.

  Further, since the warm-up completion time estimation means is performed when the start is determined in step 306 (predictive control start determination means), the estimation means by the warm-up completion time estimation means can be performed from an appropriate time.

  In the above-described embodiment, a mechanism for raising the temperature of the fuel cell 10 using a heat medium including the heat medium heating means (heater 79) 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 that detects the temperature of the heat medium that raises the temperature of the fuel cell 10 is adopted. However, the temperature sensor that directly detects the temperature of the fuel cell 10 is adopted. Also good.

  Further, in the above-described embodiment, the heating means may be configured by other than the heater 79 as long as it is provided on the fuel cell heat medium circulation circuit 73 and energized to raise the temperature of the heat medium. .

  Further, in the above-described embodiment, the order of the four condensers is changed, for example, the reformed gas condenser 31 is arranged in the uppermost stream, and the condensed refrigerant temperature> FC at the start of power generation (or before the start of power generation). The system configuration may be such that the cooling water temperature> the reformed gas FC inlet temperature. According to this, as described above, the warm-up by both can be performed at the same time without completely switching from the warm-up due to the exhaust heat of the reformer 20 to the warm-up by the heater 79, thereby shortening the warm-up time. It is also effective for warming up a fuel cell having a large heat capacity.

  Further, in the above-described embodiment, when the fuel cell power generation start condition is satisfied, the heating of the fuel cell 10 by the heater 79 may be continued after the time when the condition is satisfied. This is particularly effective for systems that have a large heat capacity and require time to warm up by self-heating of the fuel cell.

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 by this invention. It is a flowchart of the control program by the 1st control modification performed with the control apparatus shown in FIG. It is a time chart which shows operation | movement of the 1st control modification of the fuel cell system by this invention. It is a time chart which shows operation | movement of the 1st control modification of the fuel cell system by this invention. It is a flowchart of the control program by the 2nd control modification performed with the control apparatus shown in FIG. It is a time chart which shows operation | movement of the 2nd control modification of the fuel cell system by 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), 23a ... CO shift part Temperature sensor 24... Carbon monoxide selective oxidation reaction section (CO selective oxidation section) 25. Evaporator 30. Condenser 31. Reformer gas condenser 32. Anode offgas condenser 33 33 Cathode offgas Condenser for 34, Condenser for combustion gas, 40 ... Pure water device, 50 ... Water reservoir, 53 ... Reform water pump, 61-66 ... Pipe, 67 ... Bypass path, 68 ... Reform water supply pipe, 71 DESCRIPTION OF SYMBOLS ... Hot water storage tank, 72 ... Hot water storage water circulation circuit, 73 ... FC cooling water circulation circuit, 74 ... 1st heat exchanger, 75 ... Condensed refrigerant circulation circuit, 76 ... 2nd heat exchanger, 77 ... Radiator, 78 ... Bypass path, 79 ... Heater, 78a, 72a ... First and second bar Bed, 64b, 64c, 67a ... valve, P1～P3,53 ... pumps, 73a, 73b, 75a, 64a ... first to fourth temperature sensor, 90 ... control unit.

Claims (8)

A fuel cell in which a fuel gas and an oxidant gas are supplied to the fuel electrode and the oxidant electrode, respectively, and electricity is generated by their chemical reaction; and
A reformer that generates the fuel gas and supplies the fuel gas to the fuel electrode;
A fuel cell heat medium circulation circuit in which a fuel cell heat medium that exchanges heat with the fuel cell circulates;
A first heat medium circulation circuit in which a first heat medium that collects exhaust heat of the reformer circulates;
Heat exchanging means for exchanging heat between the fuel cell heat medium and the first heat medium;
A fuel cell system comprising heating means for heating the fuel cell,
Further comprising control means for controlling operation of the fuel cell system;
The control means includes
First heating control means for starting heating of the fuel cell by the first heat medium via the heat exchanging means from the start of starting the fuel cell system;
Determination means for determining whether it is necessary to heating by the heating means in a previous time to start power generation before Symbol fuel cell,
Second heating control means for starting heating of the fuel cell by the heating means when the heating by the first heat medium is finished and the judging means judges that heating by the heating means is necessary; A fuel cell system comprising: A fuel cell in which a fuel gas and an oxidant gas are supplied to the fuel electrode and the oxidant electrode, respectively, and electricity is generated by their chemical reaction; and
  A reformer that generates the fuel gas and supplies the fuel gas to the fuel electrode;
  A fuel cell heat medium circulation circuit in which a fuel cell heat medium that exchanges heat with the fuel cell circulates;
  A first heat medium circulation circuit in which a first heat medium that collects exhaust heat of the reformer circulates;
A hot water circulating circuit for circulating hot water stored in the hot water tank, a first heat exchanger for exchanging heat between the hot water and the fuel cell heat medium, the hot water and the first heat medium A second heat exchanger that exchanges heat with the hot water, and a hot water circulation means that is provided in the hot water circulation circuit and circulates the hot water, and the fuel cell heat medium and the first heat medium are Heat exchange means for exchanging heat;
  A fuel cell system comprising heating means for heating the fuel cell,
  Further comprising control means for controlling operation of the fuel cell system;
  The control means includes
  First heating control means for starting heating of the fuel cell by the first heat medium via the heat exchanging means from the start of starting the fuel cell system;
  Determination means for determining whether heating by the heating means is necessary before the time point at which power generation of the fuel cell is started;
  A fuel cell system comprising: a second heating control unit that starts heating the fuel cell by the heating unit when the determination unit determines that heating by the heating unit is necessary. In 請 Motomeko 2, and wherein the hot water circulation circuit hot water tank bypass for bypassing is provided, said first heat exchanger to the hot water flows flow path flowing through the bypass passage bypassing the hot water storage tank A fuel cell system, wherein the second heat exchanger is provided . 4. The fuel cell system according to claim 1, wherein the first heating control unit is a unit that heats the fuel cell when the reformer is warmed up . 5. 5. The fuel cell system according to claim 1, wherein the determination unit performs the determination at a time when warming up of the reformer is completed . 5. The determination unit according to claim 1, wherein the determination unit completes warming-up of the reformer, the temperature of the fuel cell heat medium is higher than a first predetermined temperature, and the fuel. It is determined whether heating by the heating means is necessary before the time when the temperature of the battery heat medium becomes higher than a temperature higher than a temperature difference from the inlet temperature of the fuel electrode of the fuel gas by a predetermined temperature and power generation of the fuel cell is started. A fuel cell system characterized by determining . The heat exchange means according to any one of claims 1 to 6 , further configured to prohibit heat exchange between the fuel cell heat medium and the first heat medium. The fuel cell system according to claim 1, wherein when it is determined that heating by the heating unit is necessary, the heat exchange unit prohibits the heat exchange . The first heat medium circulation means for circulating the first heat medium in the first heat medium circulation circuit, and the cooling means for cooling the first heat medium in any one of claims 1 to 6. A condenser for recovering heat from the fuel gas before being supplied from the reformer and flowing into the fuel electrode of the fuel cell to condense the gas,
When the determination unit determines that heating by the heating unit is necessary, the control unit controls the first heat medium to a flow rate suitable for cooling by the first heat medium circulation unit and the cooling unit. The cooling of the first heat medium is started by the fuel cell system.

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