JP5064785B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system that suppresses power consumption of auxiliary devices of the fuel cell as much as possible when the power generation of the fuel cell is not performed.

The fuel cell is generally constructed as a fuel cell system with an accompanying device. Auxiliary equipment includes auxiliary equipment such as a blower that supplies hydrogen-containing gas to the fuel cell and a pump that supplies cooling water to the fuel cell, various sensors that grasp the state of the fuel cell system, and operation of the fuel cell system. A control device or the like for controlling is included. In general, the fuel cell is connected to a commercial power source and can supply power to each power load or ancillary equipment. In the fuel cell system, electric power is supplied from the commercial power source to the auxiliary equipment from the start of the fuel cell system until the operation of the fuel cell is established, and the electric power generated by the fuel cell is established after the operation of the fuel cell is established. Is configured to be supplied to ancillary equipment (see, for example, Patent Document 1).
JP 2003-243011 (paragraph 0002, FIG. 4 etc.)

  The fuel cell system stops power generation in the fuel cell depending on the power load and other conditions and enters a standby state. In the standby state, the blower or the like that supplies the hydrogen-containing gas to the fuel cell is stopped, but the sensors that grasp the state of the fuel cell system are activated to consume power in preparation for the next activation. If power is consumed when there is no power generation of the fuel cell, the amount of power purchased from the commercial power source will increase.

  In view of the above-described problems, an object of the present invention is to provide a fuel cell system that suppresses the power consumption of auxiliary devices of the fuel cell as much as possible when there is no power generation of the fuel cell.

  In order to achieve the above object, a fuel cell system according to a first aspect of the present invention includes a fuel cell 30 linked to a commercial power supply PP, for example, as shown in FIG. An auxiliary device that is used when the fuel cell 30 generates electric power and when the fuel cell 30 does not generate electric power (a device denoted by reference numeral 100 in the figure) An auxiliary device used for generating power by the fuel cell 30 and a non-energized device at the time of stoppage that is energized when generating power of the fuel cell 30 (a device denoted by reference numerals in the 200s in the figure) In this paragraph, it is represented by reference numeral “2XX”); and a relay 71 (see, for example, FIG. 3) disposed on a cable 91 (for example, see FIG. 3) for supplying power from the commercial power supply PP to the non-energized device 2XX at the time of stop. ) And; When not performing the power generation of the battery 30, controls the relay 71 (e.g., see FIG. 3) so as to energize the intermittently stopped when not energized equipment 2XX, and a control unit 140 belonging to always energized equipment. Here, “when generating power from a fuel cell” typically means when an auxiliary device is operating with the intention of generating power in the fuel cell, regardless of whether or not the fuel cell actually generates power. It is. “When the fuel cell does not generate electricity” is typically when the fuel cell does not intend to generate electricity and the auxiliary device is stopped.

  With this configuration, the relay is controlled to intermittently energize the de-energized device when the fuel cell is not generating power, so it is consumed by the de-energized device when the fuel cell is not generating. The amount of power that is generated is suppressed. In addition, since power is always supplied to the energized device even when the fuel cell is not generating power, control of the fuel cell system is not hindered.

The fuel cell system according to the first aspect of the present invention, for example, as shown in FIG. 1, a member constituting the fuel cell system 10, the interior of the pressure when not performing power generation of the fuel cell 30 Pressure holding component member 20 (30a) in which the pressure is maintained at a positive pressure; pressure holding component member sealing means 222, 223 (which seals the inside of the pressure holding component member 20 (30a) when power generation of the fuel cell 30 is not performed) 223, 15); and a pressure holding gas supply means 221 belonging to the non-energized device at the time of stopping, which supplies the pressure holding gas m into the pressure holding component 20 (30a). Here, the positive pressure is a pressure higher than the surrounding (outside the target area).

  If comprised in this way, since the holding | maintenance gas supply means belongs to the non-energized apparatus at the time of a stop, when not generating electric power of a fuel cell, the electric energy consumed by this apparatus can be suppressed.

The fuel cell system according to the invention of claim 2, for example, as shown in FIG. 1, in the fuel cell system 10 according to claim 1, for detecting the internal pressure of the pressure holding component 20 (30a) The pressure holding component member pressure detecting means 225 (235) belonging to the non-energized device at the time of stop is further provided; the pressure detected by the control device 140 with the pressure holding component pressure detecting means 225 (235) is the first predetermined pressure. The pressure holding gas supply means 221 is operated at the following times so that the internal pressure of the pressure holding component 20 (30a) is equal to or higher than a second predetermined pressure higher than the first predetermined pressure. .

  With this configuration, when the pressure detected by the pressure-holding component pressure detecting means is equal to or lower than the first predetermined pressure, the pressure-holding gas supply means is operated, and the internal pressure of the pressure-holding component is set to the first predetermined pressure. Since the pressure is not less than the second predetermined pressure higher than the pressure, it is possible to prevent the inside of the pressure holding component from becoming lower than the surrounding pressure.

Moreover, the fuel cell system according to the invention described in claim 3 detects the internal temperature of the pressure holding component 20 (30a) in the fuel cell system 10 described in claim 2 , for example, as shown in FIG. The pressure holding component temperature detecting means 224 (234) belonging to the non-energized device at the time of stop; the passage of time when the fuel cell 30 does not generate power, and the inside of the pressure holding component 20 (30a) is the pressure holding component. The pressure around the pressure holding component 20 (30a) from the third predetermined pressure in relation to the pressure drop from the state of the third predetermined pressure at the temperature detected by the temperature detecting means 224 (234). A calculation unit 141 that calculates the internal pressure reduction time until the pressure drops to the fourth predetermined pressure.

  With this configuration, by calculating the internal pressure drop time, it becomes possible to energize the deenergized device at the stop at an appropriate timing, and energize the deenergized device at the stop when there is no power generation of the fuel cell. Can be kept to the minimum necessary.

Further, when the fuel cell system according to the invention described in claim 4 is shown with reference to FIG. 1, for example, in the fuel cell system 10 according to claim 3 , the control device 140 includes a pressure holding component member pressure detecting means. When the value detected by 225 (235) is equal to or lower than the fifth predetermined pressure, the pressure is increased by the pressure holding gas supply means 221, and then the internal pressure drop time is calculated by the calculation unit 141, and the pressure holding component member pressure detection means 225 (235) When the value detected in (1) exceeds the fifth predetermined pressure, the internal pressure reduction time is calculated by the calculation unit 141 without operating the pressure-holding gas supply means 221.

  If comprised in this way, it will become possible to prevent that the inside of a pressure-holding structural member becomes lower than the surrounding pressure.

Further, when the fuel cell system according to the invention described in claim 5 is shown, for example, with reference to FIG. 1, in the fuel cell system 10 according to claim 3 or claim 4 , the control device 140 includes the internal pressure drop time. The relay 71 (see, for example, FIG. 3) is controlled so that the pressure holding component member pressure detecting means 225 (235) and the pressure holding component member temperature detecting means 224 (234) are energized.

  If comprised in this way, it will become possible to supply with electricity to a de-energizing apparatus at a stop with appropriate timing, preventing the inside of a pressure-holding structural member becoming lower than the surrounding pressure.

Further, when the fuel cell system according to the invention described in claim 6 is shown with reference to FIG. 1, for example, in the fuel cell system according to claim 1 , the internal temperature of the pressure-holding component 20 (30a) is detected. The pressure holding component temperature detecting means 224 (234) belonging to the non-energized device at stop is provided; when the temperature detected by the control device 140 with the pressure holding component temperature detecting means 224 (234) is equal to or lower than a predetermined temperature. The pressure holding gas supply means 221 is operated.

  If comprised in this way, it will become possible by a simple structure to prevent that the inside of a pressure-holding structural member becomes lower than the surrounding pressure.

The fuel cell system according to the invention of claim 7, for example, as shown in FIG. 1, in the fuel cell system 10 according to any one of claims 1 to 5, the holding pressure components A reformer 20 that introduces a source gas m and water s, steam reforms the source gas m, and generates a reformed gas g containing hydrogen to be supplied to the fuel cell 30; The sealing means includes reformer internal sealing means 222 and 223 for sealing the inside of the reformer 20; the pressure holding gas supply means supplies the raw material gas m to the reformer 20 221.

  If comprised in this way, it will become possible to prevent that the pressure inside a reformer becomes lower than the surrounding pressure, suppressing power consumption.

The fuel cell system according to the invention of claim 8, for example, as shown in FIG. 1, in the fuel cell system 10 according to any one of claims 1 to 5, the holding pressure components The pressure holding component sealing means includes fuel electrode inner sealing means 235 and 15 for sealing the inside of the fuel electrode 30a. When power generation by the fuel cell is not performed, the air electrode 30c of the fuel cell is typically at the same pressure as the ambient pressure (typically atmospheric pressure).

  If comprised in this way, it will become possible to maintain the pressure difference of the fuel electrode of a fuel cell, and an air electrode within an allowable range, suppressing power consumption.

  According to the present invention, when the fuel cell is not generating power, the relay is controlled to intermittently energize the non-energized device when stopped. The amount of power that is generated is suppressed.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding members are denoted by the same or similar reference numerals, and redundant description is omitted. In FIG. 1, an alternate long and short dash line represents an electric cable.

  First, a mechanical configuration of a fuel cell system 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic system diagram of the mechanical configuration of the fuel cell system 10. The fuel cell system 10 includes a fuel cell 30, a reformer 20 that generates a reformed gas g containing hydrogen to be supplied to the fuel cell 30, ancillary equipment that is used for the fuel cell 30 to generate power, a fuel And a control device 140 that controls the battery system 10. Ancillary devices are always energized devices (indicated by reference numbers in the 100s in the figure), non-energized devices at stop (indicated by reference numbers in the 200s in the diagram), and energized devices in power generation It is divided roughly into. The constantly energized device is energized regardless of the power generation state of the fuel cell 30. The non-energized device at stop is energized when generating power from the fuel cell 30, and is energized intermittently without energizing when the fuel cell 30 is not generating power. The power generation energization device is energized when the fuel cell 30 generates power, and is not energized when the fuel cell 30 does not generate power. The control device 140 belongs to a constantly energized device.

  The reformer 20 is an apparatus that introduces a raw material gas m and process water s and generates a reformed gas g rich in hydrogen by a steam reforming reaction. The source gas m is typically composed mainly of hydrocarbons such as chain hydrocarbons (including natural gas) such as methane and ethane, or methanol and petroleum products (kerosene, gasoline, naphtha, LPG, etc.). A hydrocarbon-based fuel obtained by vaporizing a mixture or the like and suitable for combustion for heating is used. The process water s may be water vapor. The reformed gas g rich in hydrogen is a gas containing hydrogen as a main component, and is a gas supplied to the fuel cell 30 containing hydrogen in an amount of 40% by volume or more, typically about 70 to 80% by volume. is there. The hydrogen concentration in the reformed gas g may be 80% by volume or more, that is, any concentration that can generate power by an electrochemical reaction with oxygen in the oxidant gas t when supplied to the fuel cell 30.

  Here, with reference to FIG. 2, the structure of the reformer 20 is demonstrated in detail. FIG. 2 is a schematic longitudinal sectional view of the reformer 20. The reformer 20 includes a reforming unit 21, a shift conversion unit 22, a selective oxidation unit 23, a process water introduction pipe 24, and a heating unit 25. The reforming unit 21, the shift conversion unit 22, the selective oxidation unit 23, and the process water introduction pipe 24 are in communication with each other and are affected by internal pressure fluctuations, but these and the heating unit 25 are in communication with each other. It is comprised so that it can interrupt | block. The reformer 20 is one of the pressure-holding components, and is particularly a portion where the pressure is preferably maintained in the reforming unit 21, the shift unit 22, and the selective oxidation unit 23. The pressure holding component is a member constituting the fuel cell system 10 that preferably holds the internal pressure within a predetermined range.

  The reforming unit 21 introduces the raw material gas m and water vapor sv as water, and reforms the raw material gas m into a semi-reformed gas r1 by a steam reforming reaction. The semi-reformed gas r1 typically contains about 70% by volume of hydrogen and about 10% by volume of carbon monoxide. The reforming unit 21 is filled with a reforming catalyst 21c and is configured to promote a steam reforming reaction. Typically, a nickel-based reforming catalyst or a ruthenium-based reforming catalyst is used as the reforming catalyst 21c.

  Further, the reforming unit 21 is provided with a reforming unit temperature sensor 224 as a pressure holding component member temperature detecting means for detecting the internal temperature. The reformer temperature sensor 224 is typically disposed on the downstream side of the reforming catalyst 21c. The reforming unit temperature sensor 224 is connected to the control device 140 through a signal cable, and is configured to transmit the detected temperature in the reforming unit 21 as a signal to the control device 140.

  Further, the reforming unit 21 is connected to the shift unit 22 on the downstream side of the reforming catalyst 21c so that the semi-reformed gas r1 generated in the reforming unit 21 is sent to the shift unit 22. In the following description, “connected” includes the case of being connected via a flow path or the like. In addition, a raw material gas introduction pipe 28 for introducing the raw material gas m is connected to the reforming portion 21 upstream of the reforming catalyst 21c. An inlet solenoid valve 222 that shuts off the introduction of the source gas m to the reforming unit 21 is disposed in the source gas introduction pipe 28.

  The shift converter 22 introduces the semi-reformed gas r1 from the reformer 21, and causes the carbon monoxide contained in the semi-reformed gas r1 to undergo a shift reaction with the water contained in the semi-reformed gas r1, thereby producing carbon dioxide. And hydrogen are generated from the semi-reformed gas r1 to produce a modified gas r2 having a reduced carbon monoxide concentration. The modification reaction is an exothermic reaction. The shift unit 22 is filled with a shift catalyst 22c, and is configured to promote the shift reaction. Typically, the shift catalyst 22c is an iron-chromium shift catalyst, a copper-zinc shift catalyst, a platinum shift catalyst, or the like. The modified gas r2 generated in the shift unit 22 has a carbon monoxide concentration reduced to about 5000 to 10000 ppm. The shift unit 22 is connected to the selective oxidation unit 23 on the downstream side of the shift catalyst 22c so that the shift gas r2 generated in the shift unit 22 is sent to the selective oxidation unit 23.

  The selective oxidation unit 23 introduces the transformation gas r2 from the transformation unit 22, introduces oxygen by introducing air a (hereinafter referred to as “selective oxidation air a”) from the outside of the system, and remains in the transformation gas r2. By the selective oxidation reaction between the carbon monoxide thus introduced and the introduced oxygen, a reformed gas g having a further reduced carbon monoxide concentration is generated from the modified gas r2. The selective oxidation reaction is an exothermic reaction. The selective oxidation unit 23 is filled with a selective oxidation catalyst 23c. Typically, a platinum-based selective oxidation catalyst, a ruthenium-based selective oxidation catalyst, a platinum-ruthenium-based selective oxidation catalyst, or the like is used as the selective oxidation catalyst 23c. A selective oxidation air pipe 69 for introducing the selective oxidation air a is connected to the selective oxidation unit 23 upstream of the selective oxidation catalyst 23c. The selective oxidation air pipe 69 is provided with a selective oxidation air solenoid valve 27 that blocks introduction of the selective oxidation air a into the selective oxidation unit 23.

  As described above, the reformed gas g generated in the selective oxidation unit 23 is a gas containing hydrogen of 40% or more, typically about 75%. The carbon monoxide concentration in the reformed gas g is about 10 ppm or less. A reformed gas outlet pipe 29 for leading the reformed gas g is connected to the selective oxidation unit 23 downstream of the selective oxidation catalyst 23c. The reformed gas outlet pipe 29 is provided with an outlet solenoid valve 223 that blocks the flow of the reformed gas g. A bypass pipe 66 that guides the reformed gas g to the heating unit 25 is connected to the reformed gas outlet pipe 29 upstream of the outlet solenoid valve 223. The bypass pipe 66 is provided with a bypass solenoid valve 16 that blocks the flow of the reformed gas g. Further, the reformed gas outlet pipe 29 upstream of the outlet solenoid valve 223 is provided with an internal pressure sensor 225 as a pressure holding component member pressure detecting means for detecting the pressure inside the reformer 20. The inside of the reformer 20 is a portion in which the respective catalysts 21c, 22c, and 23c exist and gas flows. In the present embodiment, the inlet electromagnetic valve 222, the outlet electromagnetic valve 223, and the selective oxidation air electromagnetic valve 27 are provided. The space is hermetically sealed when the bypass electromagnetic valve 16 and the process water electromagnetic valve 26 described later are shut off. That is, in this embodiment, the reformer internal sealing means is constituted by the inlet solenoid valve 222, the outlet solenoid valve 223, the bypass solenoid valve 16, the process water solenoid valve 26, and the selective oxidation air solenoid valve 27.

  The process water pipe 24 is disposed adjacent to the reforming unit 21 and adjacent to the transformation unit 22 and the selective oxidation unit 23. Adjacent to the shift unit 22 and the selective oxidation unit 23 is that the heat generated by the reaction in the shift unit 22 and the selective oxidation unit 23 is close to the extent that the water s flowing in the process water pipe 24 receives heat. The amount of heat received at this time is preferably such that the liquid water s becomes gaseous water (water vapor sv) before flowing into the reforming unit 21. Further, the process water pipe 24 is disposed so as to receive heat from the reforming unit 21. If the process water s flowing through the process water pipe 24 cannot receive sufficient heat to evaporate before flowing into the reforming unit 21, it can also be received in the heating unit 25 or in the vicinity of the heating unit 25 so as to receive heat from the heating unit 25. A process water pipe 24 may be provided. A process water solenoid valve 26 is disposed in the process water pipe 24.

  The heating unit 25 typically includes a burner 25b, introduces combustion fuel and combustion air (not shown), and burns the combustion fuel to generate reforming heat. The combustion fuel is, for example, one or two of the source gas m (the introduction pipe is not shown), the anode offgas p introduced via the anode offgas line 65, and the reformed gas g. More than types are used. The anode off gas p is a gas that is discharged from the fuel cell 30 (see FIG. 1) and contains hydrogen that has not been used for the electrochemical reaction in the fuel cell 30 (see FIG. 1). The heating unit 25 is disposed in the vicinity of the reforming unit 21 to such an extent that heat used for reforming can be given to the reforming unit 21, and preferably a space is formed in the center of the reforming unit 21. Thus, when it is formed in a bamboo ring shape and disposed in the central space, the reforming heat can be effectively transmitted to the reforming section 21.

  The description will be continued with reference to FIG. A raw material gas line 61 for flowing the raw material gas m is connected to the inlet solenoid valve 222 that shuts off the introduction of the raw material gas m to the reformer 20. The source gas line 61 is provided with a source gas blower 221 as source gas supply means for pumping the source gas m.

  The fuel cell 30 is a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, and is typically a solid polymer fuel cell. The fuel cell 30 includes a fuel electrode 30a that introduces a reformed gas g, an air electrode 30c that introduces an oxidant gas t, and a cooling unit 30r that takes away heat generated by an electrochemical reaction. . The oxidant gas t is typically air. Although the fuel cell 30 is shown in a simplified manner in the drawing, in practice, a single cell is formed by sandwiching the solid polymer film between the fuel electrode 30a and the air electrode 30c, and this cell is formed in the cooling unit 30r. A plurality of layers are stacked via the. In the fuel cell 30, hydrogen in the reformed gas g supplied to the fuel electrode 30a is decomposed into hydrogen ions and electrons, and the hydrogen ions move to the air electrode 30c through the solid polymer film, and the electrons are fueled. It moves to the air electrode 30c through a conducting wire connecting the electrode 30a and the air electrode 30c, reacts with oxygen in the oxidant gas t supplied to the air electrode 30c to generate water, and generates heat during this reaction. To do. In this reaction, the direct current can be taken out by passing electrons through the conducting wire. A power conditioner 33 that converts DC power to AC power is connected to the fuel cell 30. The power conditioner 33 is connected to the commercial power supply PP and the power load EL via an electric cable.

  The fuel electrode 30a is one of the pressure holding components. The fuel electrode 30a is provided with a fuel electrode temperature sensor 234 as a pressure holding component temperature detecting means for detecting the internal temperature. In addition, a reformed gas line 62 through which the reformed gas g flows is connected to the fuel electrode 30a. The other end of the reformed gas line 62 is connected to the outlet solenoid valve 223. The fuel electrode 30 a and the heating unit 25 are connected via an anode off gas line 65 so that the anode off gas p can be introduced into the heating unit 25. An anode off gas electromagnetic valve 15 is disposed in the anode off gas line 65. A bypass pipe 66 is connected to the anode offgas line 65 on the downstream side of the anode offgas electromagnetic valve 15. By closing the outlet solenoid valve 223 and the anode off-gas solenoid valve 15, the inside of the fuel electrode 30a can be sealed. That is, in this embodiment, the outlet solenoid valve 223 and the anode off-gas solenoid valve 15 constitute a fuel electrode inner sealing means. The inside of the fuel electrode 30a is a portion through which the reformed gas g or the anode off gas p flows, and is a space that is hermetically sealed when the outlet solenoid valve 223 and the anode off gas solenoid valve 15 are shut off. Typically, the reformed gas line 62 is provided with a fuel electrode pressure sensor 235 as a pressure holding component member pressure detecting means for detecting the internal pressure of the fuel electrode. The fuel electrode pressure sensor 235 may be provided in the fuel electrode 30a as long as the internal pressure of the fuel electrode 30a can be detected, or may be provided in the anode offgas line 65 upstream from the anode offgas electromagnetic valve 15. .

  An oxidant gas line 63 for introducing the oxidant gas t is connected to the air electrode 30 c of the fuel cell 30. An oxidant gas blower 31 that pumps the oxidant gas t is disposed in the oxidant gas line 63. Further, a cathode offgas line (not shown) for discharging the cathode offgas is connected to the air electrode 30c. The cathode off-gas is a gas exhausted from the air electrode 30 c containing oxygen that has not been used for the electrochemical reaction in the fuel cell 30. A cooling water line 64 for flowing the cooling water c is connected to the cooling unit 30 r of the fuel cell 30. The cooling water line 64 is a circulation line. The cooling water line 64 is provided with a radiator (not shown) so that the temperature of the cooling water c that has risen due to heat removal from the cooling unit 30r can be lowered. The heat taken away from the cooling water c by a radiator (not shown) is typically stored in a heat storage tank (not shown), and is appropriately used in heat demand (not shown) such as hot water supply or heating. A cooling water pump 32 that circulates the cooling water c is disposed in the cooling water line 64.

  The control device 140 controls the fuel cell system 10. The control device 140 has a timer. Further, the control device 140 is connected to the calculation unit 141 and the operation plan board 142. Similarly to the control device 140, the calculation unit 141 and the operation plan board 142 are always energized devices. On the other hand, the equipment belonging to the non-energized equipment at the time of stop includes the above-described raw material gas blower 221, reformer temperature sensor 224, internal pressure sensor 225, inlet solenoid valve 222, outlet solenoid valve 223, fuel pole temperature sensor 234, fuel pole pressure. There is a sensor 235, and these unpowered devices at the time of stopping are connected to the control device 140 by signal cables. In addition, the equipment belonging to the power generation energization equipment includes an oxidant gas blower 31, a cooling water pump 32, a process water solenoid valve 26, a selective oxidation air solenoid valve 27, an anode off-gas solenoid valve 15, and a bypass solenoid valve 16. Each hourly energizing device is connected to the control device 140 by a signal cable.

  The raw material gas blower 221, the oxidant gas blower 31, and the cooling water pump 32 are typically activated and stopped (including adjustment of the rotation speed if the rotation speed is adjustable) in response to a command from the control device 140. It is configured as follows. The reformer temperature sensor 224 and the fuel electrode temperature sensor 234 can transmit the detected temperature as a signal to the control device 140, and the internal pressure sensor 225 and the fuel electrode pressure sensor 235 can transmit the detected pressure to the control device 140 as a signal. It is configured to be able to transmit. The inlet solenoid valve 222 and the outlet solenoid valve 223 are typically normally closed (non-energized) solenoid valves so that each can receive a signal from the control device 140 and open the valves. It is configured. In addition, the process water solenoid valve 26, the selective oxidation air solenoid valve 27, the anode off-gas solenoid valve 15, and the bypass solenoid valve 16 are also typically normally closed (closed when not energized) solenoid valves, respectively. The valve can be opened by receiving a signal from.

  The operation plan board 142, which is a constantly energized device, plans the timing at which the fuel cell 30 generates power in order to operate the fuel cell system 10 with high efficiency. The operation plan board 142 typically predicts electric power demand and heat demand based on past operation results, and determines the operation status of the fuel cell system 10 (whether the fuel cell 30 is generating electricity, The timing of starting (power generation) and stopping the fuel cell 30 is planned so as to achieve high efficiency operation. The reason for planning the timing of generating power by the fuel cell 30 is that the reformer 20 generates the reformed gas g before the power generation from the state where the fuel cell 30 is stopped, and the fuel cell 30 is suitable for power generation. This is because the auxiliary equipment is operated prior to the start of power generation of the fuel cell 30 in order to raise the temperature to a high temperature.

  The operation unit 141 that is a constantly energized device stores in advance the relationship between the passage of time when the power generation of the fuel cell 30 is not performed and the pressure drop inside the reformer 20, and the fourth predetermined pressure is calculated from the third predetermined pressure. The time until the pressure is reduced to the predetermined pressure (internal pressure reduction time) can be calculated. Here, the third predetermined pressure is typically a pressure at which the internal pressure of the reformer 20 can be maintained at a positive pressure without immediately increasing the internal pressure of the reformer 20. . The fourth predetermined pressure here is typically a pressure at which the internal pressure of the reformer 20 can safely maintain a positive pressure (pressure at which ambient air does not enter the reformer 20). Among these, there is a margin (a buffer zone in which the reformer 20 is not adversely affected as soon as it falls below the threshold). The internal pressure drop time varies depending on the temperature difference at that time even at the same third predetermined pressure. For example, the reformer 20 when the third predetermined pressure is 50 kPa (gauge pressure) than when the internal temperature of the reformer 20 when the third predetermined pressure is 50 kPa (gauge pressure) is 600 ° C. When the internal temperature is 350 ° C., the internal pressure drop time becomes longer. Accordingly, the calculation unit 141 is configured to take in the temperature and pressure values inside the reformer 20 from the control device 140 and calculate the internal pressure decrease time. The relationship between the passage of time when the power generation of the fuel cell 30 is not performed and the pressure drop inside the reformer 20 may be stored as a table in the calculation unit 141 or may be stored as a mathematical expression.

  In addition, the calculation unit 141 stores in advance a relationship between the passage of time when the power generation of the fuel cell 30 is not performed and the pressure drop inside the fuel electrode 30a, and the first is determined from the pressure when the fuel electrode 30a is sealed. The time until the pressure is reduced to a predetermined pressure (fuel electrode pressure drop time) can be calculated. When the power generation of the fuel cell 30 is not performed, the fuel electrode 30a is sealed from the viewpoint of electrode protection. The pressure when sealing the fuel electrode 30a is higher than the pressure of the air electrode 30c that is open when the fuel cell 30 is not generating power (equal to the pressure around the fuel cell 30, typically atmospheric pressure). The upper limit is such that the solid polymer film existing between the fuel electrode 30a and the air electrode 30c is not reliably damaged. The first predetermined pressure here is typically the lowest pressure in the range of the pressure difference from the air electrode 30c so as not to damage the solid polymer membrane of the fuel cell 30 reliably. A buffer zone is included so that the solid polymer membrane is not damaged as soon as it falls below the threshold. The relationship between the passage of time when the power generation of the fuel cell 30 is not performed and the pressure drop in the fuel electrode 30a may be stored in the calculation unit 141 as a table or may be stored as a mathematical expression.

  The control device 140, the calculation unit 141, and the operation plan board 142 are typically housed in a single casing, but may be arranged separately. In addition to the control device 140, the calculation unit 141, and the operation plan board 142, as a constantly energized device, in order to measure the start timing of the anti-freezing measures in the gas sensor 151 that detects the leakage of flammable gas and in cold regions. It is preferable to provide an external temperature sensor 152 for detecting the outside air temperature. Since it is possible to estimate the temperature drop of the reformer 20 or the fuel cell 30 over time when the power generation of the fuel cell 30 is not performed, the external temperature sensor 152 is provided, and the calculation unit 141 corrects the temperature appropriately according to the outside air temperature. The internal pressure drop time and the fuel electrode pressure drop time may be calculated. When calculating the internal pressure decrease time, it is preferable to correct the temperature considering the temperature of the fuel electrode 30a in addition to the outside air temperature. In the present embodiment, in addition to the gas sensor 151 and the external temperature sensor 152, for example, a communication power source (not shown), a power measuring unit power source, a relay power source for supplying power to each relay described later, etc. are included in the constantly energized device. It is.

  Next, the electrical configuration of the fuel cell system 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a connection diagram of the electric system of the fuel cell system 10. The fuel cell system 10 is linked to a commercial power supply PP via a cable 81. A cable 82 for transmitting power to the power load EL is connected to the cable 81. The cable 81 is connected to a cable 83 and a cable 88 in the fuel cell system 10.

  A cable 84 (84a) and a cable 91 (91a) are connected to the cable 83. The cable 84 is provided with a DC stabilized power source 73 that uses a commercial AC power source as a DC power source. Use of a stabilized DC power supply is preferable because it is less susceptible to input fluctuations and load fluctuations. A cable 85 and a cable 86 (86a) are connected to the cable 84b on the downstream side of the DC stabilized power supply 73.

  The cable 85 is a cable that transmits power to the control device 140, the calculation unit 141, and the operation plan board 142. In FIG. 3, for simplicity, the control device 140, the calculation unit 141, and the operation plan board 142 are surrounded by a one-dot chain line, but the control device 140, the calculation unit 141, and the operation plan board 142 are enclosed in the one-dot chain line. Separate cables are installed to supply power. Alternatively, power may be transmitted to the control device 140, and power may be transmitted from the control device 140 to the calculation unit 141 and the operation plan board 142.

  A cable 87 is connected to the cable 86. The cable 87 is a cable that transmits power to the gas sensor 151, the external temperature sensor 152, a communication power source (not shown), a power measuring unit power source, and the like. Also after the cable 87, typically, cables are individually laid on the gas sensor 151, the external temperature sensor 152, and the like. The cable 86b is connected to a blocking diode 77 that allows current to flow only in one direction from the primary side to the secondary side. The fuel cell system 10 has a plurality of blocking diodes, and the terms “primary side” and “secondary side” are used in the above meaning for any blocking diode. Based on the above points, the cable 86 b is connected to the secondary side of the blocking diode 77.

  A relay 71 is disposed on the cable 91 connected to the cable 83. The relay 71 is typically an a-contact (normally open) relay. A cable 91 b on the downstream side of the relay 71 is connected to a direct current stabilized power supply 74. A cable 92 is connected to the downstream side of the direct current stabilizing power source 74. The cable 92 is connected to the primary side of the blocking diode 78. The cable 92 is connected to a battery 75 that discharges in an emergency (power failure) via a cable 99 provided with an a-contact relay 72. The battery 75 may be installed as necessary.

  A cable 93 is connected to the secondary side of the blocking diode 78. A cable 94, a cable 96, and a cable 98 are connected to the cable 93. The other end of the cable 98 is connected to the secondary side of the blocking diode 79. The fuel cell 30 is connected to the primary side of the blocking diode 79 via a cable 97. A cable 89 is connected in the middle of the cable 97, and the other end of the cable 89 is connected to the power conditioner 33. Moreover, the cable 88 is connected to the power conditioner 33, and the other end of the cable 88 is connected to the cable 81 linked to the commercial power supply PP as described above.

  A cable 96 connected to the cable 93 on the secondary side of the blocking diode 78 is connected to a power generation energizing device such as the anode offgas electromagnetic valve 15. That is, the cable 96 is a cable for transmitting power to the energization device during power generation. Although shown in a simplified manner in FIG. 3, typically, cables are individually laid on each power generating energization device within a one-dot chain line. Each individually laid cable is typically provided with a relay (not shown). If a relay (not shown) is provided so as to correspond to each energizing device at the time of power generation, power can be selectively supplied, so that power can be supplied to devices that do not need to supply power. Can be prevented.

  On the other hand, a cable 95 </ b> A and a cable 95 </ b> B are connected in the middle of the cable 94 connected to the cable 93 on the secondary side of the blocking diode 78. The cable 95 </ b> A is a cable that transmits power to the reforming unit temperature sensor 224, the internal pressure sensor 225, the fuel electrode temperature sensor 234, and the fuel electrode pressure sensor 235. In FIG. 3, each sensor 224, 225, 234, and 235 is simply surrounded by a one-dot chain line, but a separate cable is provided for each sensor 224, 225, 234, and 235 within the one-dot chain line. It is laid and supplied with power. A relay (not shown) may be provided for each cable (not shown) connected to each sensor 224, 225, 234, 235. The cable 95 </ b> B is a cable that transmits power to the raw material gas blower 221, the inlet solenoid valve 222, and the outlet solenoid valve 223. In FIG. 3, the raw material gas blower 221, the inlet electromagnetic valve 222, and the outlet electromagnetic valve 223 are shown surrounded by a one-dot chain line, but the raw material gas blower 221, the inlet electromagnetic valve 222, and the outlet electromagnetic valve 223 are shown within the one-dot chain line. A separate cable is laid on each side to supply power. Typically, each of the cables (not shown) connected to the raw material gas blower 221, the inlet solenoid valve 222, and the outlet solenoid valve 223 is provided with a relay (not shown).

  The cable 94 is connected to the primary side of the blocking diode 77. By connecting the electrical system as described above, the power supplied from the DC stabilized power supply 73 is always supplied to energized devices (devices labeled with the 100s in the figure), but is not energized when stopped. It is configured not to be supplied to the devices (devices labeled with numbers in the 200s in the figure) and the power generation energization devices (see paragraph 0040). In addition, the power generated by the fuel cell 30 and the power supplied from the DC stabilized power source 74 (including the power supplied from the battery 75 in an emergency) are always energized devices, non-energized devices when stopped, and energized when power is generated. It can be supplied to any of the devices.

  The operation of the fuel cell system 10 will be described with reference to the drawings. When the control device 140 issues a command to start power generation of the fuel cell 30 based on the operation plan created on the operation plan board 142 in a state where the fuel cell 30 is not generating power, the contact of the relay 71 is closed. The AC power supplied from the commercial power supply PP is converted into DC power by the DC stabilizing power supply 74 and then supplied to the non-energized device at the time of stop and the energized device at the time of power generation. And the control apparatus 140 ignites the burner 25b of the heating part 25 of the reformer 20, and heats the reformer 20.

  When the temperature detected by the reforming unit temperature sensor 224 reaches a temperature suitable for reforming the raw material gas m (for example, about 600 ° C.), the controller 140 activates the raw material gas blower 221 and opens the inlet electromagnetic valve 222 to start the raw material. The gas m is introduced into the reforming unit 21 and the process water electromagnetic valve 26 is opened to introduce the process water s. In the reformer 20, the raw material gas m is steam reformed to produce a hydrogen-rich reformed gas g, but the composition of the reformed gas g is not stable for a while after the reforming is started (typically allowed). Therefore, the outlet solenoid valve 223 is not opened and the reformed gas is opened via the bypass pipe 66 until the composition of the reformed gas g is stabilized. g is guided to the heating unit 25 and burned by the burner 25b to generate reforming heat used for steam reforming in the reforming unit 21.

  The operation in the reformer 20 is as follows. First, the raw material gas m and the steam sv are introduced into the reforming unit 21, receive the reforming heat from the heating unit 25, the raw material gas m is steam reformed, and is semi-reformed containing hydrogen monoxide but containing carbon monoxide. Gas r1 is generated. The semi-reformed gas r1 includes, for example, about 70% by volume of hydrogen, about 10% by volume of carbon monoxide, and other gases such as water vapor.

  The semi-reformed gas r1 is sent from the reforming section 21 to the shift section 22, and shift reaction with water vapor is performed by the action of the shift catalyst 22c to generate the shift gas r2. The modified gas r2 has a carbon monoxide concentration reduced to about 5000 to 10,000 ppm. The shift reaction in the shift section 22 is an exothermic reaction, and the heat generated in the shift section 22 is used to heat the process water s flowing in the process water introduction pipe 24.

  The shift gas r <b> 2 is sent from the shift unit 22 to the selective oxidation unit 23. At the same time, the selective oxidation air solenoid valve 27 is opened and the selective oxidation air a is introduced into the selective oxidation unit 23. In the selective oxidation unit 23, carbon monoxide in the introduced modified gas r2 reacts with oxygen in the selectively oxidized air a (selective oxidation reaction) to generate carbon dioxide, so that monoxide is oxidized more than the modified gas r2. A reformed gas g having a reduced carbon concentration is generated. The reformed gas g produced by the selective oxidation reaction has a carbon monoxide concentration reduced to about 10 ppm or less. The selective oxidation reaction in the selective oxidation unit 23 is also an exothermic reaction, and the heat generated in the selective oxidation unit 23 is used to heat the process water s flowing in the process water introduction pipe 24.

When the composition of the reformed gas g is stabilized for a while after the reforming is started, the control device 140 closes the bypass solenoid valve 16 and opens the outlet solenoid valve 223 so that the reformed gas g is fed to the fuel electrode 30a of the fuel cell 30. At the same time, the oxidant gas blower 31 is activated to supply the oxidant gas t to the air electrode 30c. In the fuel cell 30, an electrochemical reaction is performed between hydrogen in the reformed gas g introduced into the fuel electrode 30a and oxygen in the oxidant gas t introduced into the air electrode 30c. As for the electrochemical reaction, the reaction shown in the following formula (1) is performed on the fuel electrode 30a side, and the reaction shown in the following formula (2) is performed on the air electrode 30c side.
2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
Electricity is generated by this electrochemical reaction, heat is generated, and moisture is generated. In further explanation, DC power can be obtained when electrons on the fuel electrode 30a side move to the air electrode 30c side through the external electric circuit. Hydrogen ions on the fuel electrode 30a side pass through the solid polymer film and move to the air electrode 30c side, and combine with oxygen to generate moisture. This electrochemical reaction is an exothermic reaction.

  Further, the control device 140 activates the cooling water pump 32, removes heat generated by the electrochemical reaction in the fuel cell 30 with the cooling water c, and sets the temperature of the fuel cell 30 to an appropriate operating temperature (for example, about 80 ° C.). ). The cooling water c whose temperature has been increased by removing the heat generated by the fuel cell 30 is radiated to another heat medium (typically water) by a radiator (not shown), and this heat is transferred to a heat storage tank (not shown). The heat is stored and used appropriately in heat demand (not shown) such as hot water supply and heating.

  When power is actually generated in the fuel cell 30 and the power generated by the fuel cell 30 can cover the power consumption of the non-energized device at stop and the energized device during power generation, the control device 140 releases the contact of the relay 71, The supply of power from the commercial power supply PP to the DC stabilized power supply 74 is stopped. Further, when the power generated by the fuel cell 30 can cover the power consumption of the constantly energized device, the direct current stabilized power source 73 refuses to receive power from the commercial power source PP. Further, the electric power generated by the fuel cell 30 is converted into alternating current by the power conditioner 33 and then supplied to the electric power load EL. The power load EL is also typically supplied with power from the commercial power supply PP.

  Now, in a state where the fuel cell 30 is generating power, the control device 140 refers to the operation plan created on the operation plan board 142 and refers to the state of the fuel cell system 10 (for example, the amount of heat stored in the heat storage tank (not shown)). ), And when it is determined that the power generation of the fuel cell 30 should be stopped in consideration of the state of the power load EL, the operation shifts to the operation of stopping the power generation of the fuel cell 30.

  When stopping the power generation of the fuel cell 30, the oxidant gas blower 31 is stopped. When the power generation of the fuel cell 30 is not performed, the air electrode 30c is opened to the atmosphere. On the other hand, the fuel electrode 30a side when stopping the power generation of the fuel cell 30 first closes the anode off-gas electromagnetic valve 15 and then closes the outlet electromagnetic valve 223, so that the reformed gas g is placed inside the fuel electrode 30a. Is enclosed. Thereafter, the raw material gas blower 221 is stopped and the inlet solenoid valve 222, the process water solenoid valve 26, and the selective oxidation air electromagnetic valve 27 are closed, and the process water s, the raw material gas m, and the selective oxidation air a to the reformer 20 are closed. Stop supplying. Thereby, the inside of the reformer 20 is sealed with the semi-reformed gas r1 or the like. The bypass solenoid valve 16 is closed when the reformed gas g is supplied to the fuel electrode 30a, and the bypass solenoid valve 16 is kept closed even when the power generation of the fuel cell 30 is stopped. As described above, the inside of the reformer 20 is sealed with the semi-reformed gas r1 or the like so as to have a positive pressure from the outside (typically the atmosphere), thereby allowing the outside air to enter the reformer 20. Intrusion is prevented, and the reforming catalyst 21c, the shift catalyst 22c, and the selective oxidation catalyst 23c are prevented from deteriorating due to contact with oxygen.

  By the way, the temperature of the reformer 20 during steady operation is about 600 ° C. as described above, but when the reformer 20 stops due to the stop of power generation of the fuel cell 30, the temperature of the reformer 20 decreases. To do. When the temperature of the reformer 20 decreases while the interior of the reformer 20 is sealed, the pressure inside the reformer 20 decreases, and when the negative pressure is reached, outside air may invade. The catalyst, particularly the shift catalyst 22c will be deteriorated. In order to prevent this, the control device 140 closes the contact of the relay 71 when the pressure inside the reformer 20 is equal to or lower than the first predetermined pressure, opens the inlet electromagnetic valve 222 and activates the raw material gas blower 221. At this time, if there is a relay (not shown) other than the relay 71 to energize the raw material gas blower 221 and the inlet solenoid valve 222, the control device 140 also closes the contacts of those relays. By opening the inlet electromagnetic valve 222 and starting the raw material gas blower 221, the raw material gas m is introduced into the reformer 20, and the internal pressure of the reformer 20 is set to a second predetermined pressure or higher. Maintain pressure. If the inside of the reformer 20 is maintained at a positive pressure using the raw material gas m, a special facility required when using other gases is not required, and the system can be simplified. Here, the first predetermined pressure is typically the same pressure as the above-mentioned fourth predetermined pressure (see paragraph 0043). In addition, the second predetermined pressure here is typically a pressure that increases the internal pressure of the reformer 20 as much as possible without damaging the reformer 20. The aforementioned third predetermined pressure (see paragraph 0043) may be the same pressure as the second predetermined pressure here.

  When there is no power generation in the fuel cell 30, the raw material gas blower 221, which is a non-energized device at the time of stop, is energized (intermittently energized) when starting to maintain the internal pressure of the reformer 20 at a positive pressure. Therefore, power consumption can be suppressed. In addition, when there is no power generation in the fuel cell 30, the normally closed solenoid valves 15, 16, 26, 27, which are normally energized devices during power generation, are not energized, and the normally closed inlet solenoids, which are non-energized devices when stopped. Since the valve 222 and the outlet solenoid valve 223 are energized (energized intermittently) when starting to maintain the internal pressure of the reformer 20 at a positive pressure, power consumption can be suppressed. Further, when there is no power generation in the fuel cell 30, the internal pressure sensor 225 that detects whether or not the internal pressure of the reformer 20, which is a de-energized device at the time of stoppage, is equal to or lower than a first predetermined pressure, Since power is supplied when starting to maintain the internal pressure of 20 at a positive pressure (power is supplied intermittently), power consumption can be suppressed.

  When there is no power generation in the fuel cell 30, the power consumption can be suppressed as the total time for energizing the internal pressure sensor 225 is shorter. Therefore, the control device 140 detects the internal pressure of the reformer 20 with the internal pressure sensor 225, detects the temperature of the reforming unit 21 at that time with the reforming unit temperature sensor 224, and decreases the internal pressure with the calculation unit 141. Let the time be calculated. The control device 140 closes the contact point of the relay 71 and energizes the internal pressure sensor 225 and the reforming unit temperature sensor 224 when the internal pressure decrease time calculated by the calculation unit 141 has elapsed. In this way, the power consumption of the internal pressure sensor 225 and the reforming unit temperature sensor 224 can be suppressed to the minimum necessary.

  When steam is present inside the reformer 20, the expected pressure decrease gradient may not be applied. In addition, due to other circumstances, the ratio between the internal pressure decrease time and the internal pressure decrease of the reformer 20 may deviate from the value calculated by the calculation unit 141. Therefore, the control device 140 energizes the internal pressure sensor 225 and the reforming unit temperature sensor 224 once or a plurality of times while the internal pressure reduction time elapses, and changes the internal pressure of the reformer 20 and the temperature of the reforming unit 21. It may be detected. When the pressure detected by the internal pressure sensor 225 is equal to or lower than the fifth predetermined pressure, the control device 140 introduces the raw material gas m into the reformer 20 by the raw material gas blower 221 to reduce the internal pressure of the reformer 20. The internal pressure drop time is calculated after increasing the pressure to the third predetermined pressure (see paragraph 0043) or more, preferably the second predetermined pressure (see paragraph 0065), and the pressure detected by the internal pressure sensor 225 is the fifth pressure. When the predetermined pressure is exceeded, the internal pressure reduction time may be calculated without starting the raw material gas blower 221. The fifth predetermined pressure here is the same pressure as the above-mentioned third predetermined pressure in the present embodiment.

  Further, as described above, when steam is present in the reformer 20, the ratio between the internal pressure reduction time and the internal pressure drop of the reformer 20 may deviate from the value calculated by the calculation unit 141. Therefore, the material gas blower 221 may be intermittently operated based on the temperature detected by the reforming unit temperature sensor 224 without energizing the internal pressure sensor 225. In this case, the raw material gas blower 221 may be started for a large margin (that is, in view of safety so that the inside of the reformer 20 does not become negative pressure). When the internal pressure sensor 225 is not used, the internal pressure sensor 225 need not be provided.

  In addition to the reformer 20, the internal pressure of the fuel electrode 30a of the fuel cell 30 may decrease due to a decrease in temperature or a reaction between hydrogen and oxygen remaining therein. The temperature of the fuel cell 30 during steady operation is about 80 ° C., but when the power generation of the fuel cell 30 is stopped, the temperature of the fuel cell 30 decreases. When the temperature of the fuel cell 30 decreases, the internal pressure of the sealed fuel electrode 30a decreases when the fuel cell 30 stops, and the pressure difference from the open air electrode 30c increases when the fuel cell 30 stops. If the differential pressure between the fuel electrode 30a and the air electrode 30c increases, the solid polymer film may be damaged. To prevent this, the control device 140 determines that the pressure inside the fuel electrode 30a is the first predetermined pressure. At the following time, the contact of the relay 71 is closed (when there is a relay (not shown) other than the relay 71 in order to energize the outlet solenoid valve 223, the contact of the relay is also closed), and the outlet solenoid valve 223 is opened. When the outlet solenoid valve 223 is opened, the reformed gas g enclosed in the reformer 20 flows into the fuel electrode 30 a having a lower pressure than the interior of the reformer 20. At this time, the control device 140 energizes the fuel electrode pressure sensor 235 to detect the internal pressure of the fuel electrode 30a, and closes the outlet solenoid valve 223 when the internal pressure of the fuel electrode 30a reaches the second predetermined pressure. The inside of the fuel electrode 30a is again sealed. In this manner, the inside of the fuel electrode 30a is set to a pressure (second predetermined pressure (here, typically a pressure when sealing the inside of the fuel electrode 30a) so as not to damage the solid polymer film. Hold. In the case of the present embodiment, the outlet solenoid valve 223 serves as a pressure holding gas supply means, and the gas (reformed gas g or the like) sealed inside the reformer 20 serves as the pressure holding gas.

  When the gas sealed inside the reformer 20 flows into the fuel electrode 30a, the internal pressure of the reformer 20 decreases. In this case, the inlet solenoid valve 222 is opened and the raw material gas blower is opened. 221 is activated to restore the internal pressure of the reformer 20. If the internal pressure of the fuel electrode 30a cannot be increased to the second predetermined pressure simply by opening the outlet solenoid valve 223, the inlet solenoid valve 222 is opened while the outlet solenoid valve 223 is opened, and the raw material The gas blower 221 is activated, and the fuel electrode 30a is first boosted to a second predetermined pressure, the outlet solenoid valve 223 is closed, and then the raw material gas m is supplied to the interior of the reformer 20 to supply the interior of the reformer 20. May be maintained at a positive pressure. In this case, in addition to the outlet solenoid valve 223, the raw material gas blower 221 and the inlet solenoid valve 222 also serve as pressure holding gas supply means.

  Even when holding pressure control of the fuel electrode 30a, when there is no power generation in the fuel cell 30, the outlet solenoid valve 223 which is a non-energized device at the time of stop (including the raw material gas blower 221 and the inlet solenoid valve 222 as necessary) Is energized (intermittently energized) when it is opened to hold the fuel electrode 30a, so that power consumption can be suppressed. Further, when there is no power generation in the fuel cell 30, the power consumption can be suppressed as the total time during which the fuel electrode pressure sensor 235 is energized is shorter. Therefore, the control device 140 changes the internal pressure of the fuel electrode 30 a to the second pressure. The temperature at the predetermined pressure is detected by the fuel electrode temperature sensor 234 and the calculation unit 141 calculates the fuel electrode pressure decrease time. The control device 140 calculates the fuel electrode pressure decrease time calculated by the calculation unit 141. When the time elapses, the contact of the relay 71 may be closed and the fuel electrode temperature sensor 234 and the fuel electrode pressure sensor 235 may be energized. In this way, the power consumption of the fuel electrode temperature sensor 234 and the fuel electrode pressure sensor 235 can be minimized.

  In addition to what has been described so far, preferably, when there is no power generation in the fuel cell 30, the gas sensor 151 of the fuel cell system 10 is preferably operated at all times to monitor the presence or absence of leakage of combustible gas. The gas sensor 151 transmits a signal to the control device 140 when the leakage of the combustible gas is detected, and the control device 140 that has received the signal stops the fuel cell system 10. Further, preferably, the temperature sensor 152 is always operated under a weather condition that may cause freezing, and anti-freezing measures are performed as necessary (such as operating a non-illustrated anti-freezing heater or moving a fluid in the pipe). It is good to take.

  In the above description, the reformer 20 and the fuel electrode 30a of the fuel cell 30 have been described as pressure-holding components, but other members constituting the fuel cell system 10 (for example, a desulfurizer, a humidifier, a conduit, condensed water) Tanks, blowers, heat exchangers, etc.) may be used as pressure-holding components as necessary.

  In the above description, the reforming part temperature sensor 224 and the fuel electrode temperature sensor 234 that directly detect the internal temperature of the pressure holding component member are used as the pressure holding component temperature detection unit. The pressure holding component, such as by calculation from the temperature of another part in which the temperature change of the member is reflected (including the temperature detected by the sensor detecting the temperature of the other pressure holding component, the external temperature sensor 152, etc.) It is also possible to indirectly detect the internal temperature. Moreover, although the internal sensor 225 and the fuel electrode pressure sensor 235 that directly detect the internal pressure of the pressure holding member are used as the pressure holding member pressure detecting means, it may be detected indirectly. .

  In the above description, the sensor that detects the internal temperature of the reformer is the reforming unit temperature sensor that detects the temperature of the reforming unit 21. A selective oxidation unit temperature sensor that detects the temperature of the oxidation unit 23 may be used. However, a reforming section temperature sensor that detects the temperature of the reforming section 21 that is the highest temperature during operation of the reforming apparatus 20 is preferable because it is easy to predict changes in the internal pressure of the reforming apparatus 20.

  In the above description, the heating unit 25 has the burner 25b. However, if the heat of reforming used for the steam reforming reaction in the reforming unit 21 can be generated, for example, an electric heater or the like can be used instead of the burner 25b. Any known heating means may be used.

  In the above description, the gas sealed in the reformer 20 is used as the pressure holding gas of the fuel electrode 30a. However, a pressure holding gas may be separately supplied into the fuel electrode 30a. In this case, for example, a blower is separately provided as the pressure holding gas supply means. In this way, the internal pressure of the reformer 20 is not affected by maintaining the pressure inside the fuel electrode 30a.

  In the above description, when the power generation of the fuel cell 30 is not performed, the solid polymer film does not damage the control for maintaining the internal pressure of the reformer 20 at a positive pressure and the internal pressure of the fuel electrode 30a of the fuel cell 30. Although it has been described that the control is performed to maintain the pressure at such a pressure, the temperature at which the fuel cell 30 generates power is high, and when the power generation is stopped, the internal pressure drop accompanying the temperature drop appears more prominently The control for maintaining the internal pressure of the vessel 20 at a positive pressure may be performed, and the control for maintaining the pressure inside the fuel electrode 30a may not be performed. In this case, the outlet solenoid valve 223 can be an energization device during power generation rather than a non-energization device during stop, and the power consumption can be suppressed.

  In the above description, the reformer 20 and the fuel electrode 30a are separately sealed. However, the reformer 20 and the fuel electrode 30a are collectively connected (the reformer 20 and the fuel electrode 30a communicate with each other). May be sealed). In addition, other members constituting the fuel cell system 10 (for example, a desulfurizer, a humidifier, a conduit, a condensed water tank, a blower, a heat exchanger, etc.) may be collectively sealed as necessary. It is good also as sealing in a unit.

  In the above description, the fuel cell 30 has been described as a solid polymer fuel cell, but it may be a fuel cell other than a solid polymer fuel cell such as a phosphoric acid fuel cell. However, the polymer electrolyte fuel cell can be operated at a relatively low temperature and can be downsized, so that it is suitable for installation in a general household.

1 is a schematic system diagram of a mechanical configuration of a fuel cell system according to an embodiment of the present invention. It is a typical longitudinal cross-sectional view of a reformer. It is a connection diagram of the electric system of the fuel cell system according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell system 15 Anode off-gas solenoid valve 20 Reformer 30 Fuel cell 30a Fuel electrode 71 Relay 91 Cable 140 Control apparatus (always energized equipment)
141 Calculation unit (always energized equipment)
221 Raw material gas blower (raw material gas supply means)
222 Inlet solenoid valve 223 Outlet solenoid valve 224 Reformer temperature sensor 225 Internal pressure sensor 234 Fuel electrode temperature sensor 235 Fuel electrode pressure sensor g Reformed gas m Material gas s Water PP Commercial power supply

Claims (8)

A fuel cell linked to a commercial power source;
An auxiliary device used for power generation by the fuel cell, and a normally energized device that is energized when the fuel cell generates power and when the fuel cell does not generate power;
An auxiliary device used to generate power by the fuel cell, and a non-energized device at the time of stopping when the fuel cell generates power;
A relay disposed on a cable for supplying power from the commercial power source to the non-energized device at the time of stopping;
A control device belonging to the constantly energized device, which controls the relay to intermittently energize the non-energized device at the time of stopping when the fuel cell does not generate electricity ;
A pressure-holding component that constitutes the fuel cell system, and maintains an internal pressure at a positive pressure when the fuel cell does not generate power;
Pressure-holding component sealing means for sealing the inside of the pressure-holding component when the fuel cell does not generate electricity;
A pressure holding gas supply means belonging to the non-energized device at the time of stopping, which supplies a pressure holding gas into the pressure holding component;
Fuel cell system. A pressure holding component member pressure detecting unit belonging to the non-energized device at the time of stop, which detects an internal pressure of the pressure holding component member;
The control device operates the pressure-holding gas supply means when the pressure detected by the pressure-holding constituent member pressure detecting means is equal to or lower than a first predetermined pressure, and sets the internal pressure of the pressure-holding constituent member to the first pressure. Configured to be greater than or equal to a second predetermined pressure higher than the predetermined pressure of;
The fuel cell system according to claim 1 . Pressure-holding component temperature detection means belonging to the non-energized device at the time of stop, which detects an internal temperature of the pressure-holding component;
The passage of time when the fuel cell does not generate power, and the pressure drop from when the inside of the pressure-holding component is at the third predetermined pressure at the temperature detected by the pressure-holding component temperature detecting means, A calculating unit that calculates an internal pressure decrease time from when the third predetermined pressure is decreased to a fourth predetermined pressure that is equal to or higher than the pressure around the pressure holding component;
The fuel cell system according to claim 2 . When the value detected by the pressure-holding component pressure detector is equal to or lower than a fifth predetermined pressure, the controller causes the pressure to be increased by the pressure-holding gas supply means, and then the calculation unit calculates the internal pressure decrease time. When the value detected by the pressure holding component member pressure detecting means exceeds the fifth predetermined pressure, the internal pressure drop time is calculated by the calculation unit without operating the pressure holding gas supply means. Was;
The fuel cell system according to claim 3 . The control device controls the relay to energize the holding pressure component pressure detecting means and the holding pressure member temperature detecting means when the internal pressure drop time has elapsed;
The fuel cell system according to claim 3 or 4 . A pressure holding component temperature detecting means for detecting an internal temperature of the pressure holding component and belonging to the non-energized device at the time of stopping;
The controller is configured to operate the pressure-holding gas supply means when the temperature detected by the pressure-holding component temperature detecting means is equal to or lower than a predetermined temperature;
The fuel cell system according to claim 1 . The holding pressure component includes a reformer that introduces a source gas and water, steam reforms the source gas, and generates a reformed gas containing hydrogen to be supplied to the fuel cell;
The pressure-holding component sealing means includes a reformer internal sealing means for sealing the interior of the reformer;
The pressure-holding gas supply means comprises source gas supply means for supplying the source gas to the reformer;
The fuel cell system according to any one of claims 1 to 5. The pressure-holding component includes a fuel electrode of the fuel cell;
The pressure-holding component sealing means includes a fuel electrode internal sealing means for sealing the inside of the fuel electrode;
The fuel cell system according to any one of claims 1 to 5.

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