JP6452744B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

In the fuel cell system, as a configuration for improving energy utilization efficiency, a plurality of fuel cell stacks are provided, and unreacted fuel gas in the used fuel gas discharged from the preceding fuel cell stack is used as the subsequent fuel cell. A multi-stage type that is reused as a regenerated fuel gas in a stack is known. If the multistage fuel cell system can remove water vapor and carbon dioxide (CO ₂ ) contained in the spent fuel gas, the concentration of hydrogen and carbon monoxide contributing to the reaction will increase, so that the regenerated fuel gas will be supplied. The fuel cell stack performance is expected to improve.

  Here, although not a multistage fuel cell system, in a fuel cell in which two or more modules in which a plurality of hollow cells are connected in parallel are connected in series, a fuel that efficiently takes out current from each hollow cell and increases power generation efficiency A battery is disclosed (see Patent Document 1).

  Patent Document 2 discloses a fuel cell including a fuel cell container, a cell assembly, an anode-side electrical extraction unit, and a cathode-side electrical extraction unit.

  In Patent Document 2, each electrode takeout part of the fuel cell container takes out the electricity generated by the cell assembly to the outside of the fuel cell container.

  Further, Patent Document 3 includes a fuel battery cell, and a cover member and a base member that form a container part that forms a cell chamber for housing the fuel battery cell, for extracting electricity from the fuel battery cell. A structure is described in which an electrical connection member that connects the electrode rods is spaced from the peripheral member.

JP 2007-66723 A JP 2007-66723 A JP 2007-66723 A

  For example, in a multistage fuel cell system, it is housed in a hot box that is configured with a heat insulating material as a main material so that the atmosphere is higher than the outside air. An electrode (terminal) extraction portion attached to the stack module accommodated in the hot box penetrates the hot box and is electrically connected to the outside.

  However, since the heat insulation of the hot box is impaired due to the penetration of the electrodes, it is necessary to add fuel to compensate for the heat corresponding to the heat insulation loss, which adversely affects the power generation efficiency. Therefore, when priority is given to temperature maintainability in the hot box for maintaining power generation efficiency, it is better that the number of electrodes penetrating the hot box is small. The minimum necessary number of electrodes may be two terminals, an anode (plus) terminal and a cathode (minus) terminal.

  On the other hand, when priority is given to the versatility of the connection state of a plurality of fuel cell stack groups and a plurality of stack modules constituting each stage, the anode terminal and cathode terminal of each fuel cell stack group (and stack module) are hot. It is better to penetrate from the box. The maximum is the number of each anode terminal and cathode terminal of the stack module.

  Note that the voltage or current of the fuel cell stack group or stack module individually connected to the power conditioner or the like is controlled by the power conditioner or the like. Hereinafter, individually connecting to a power conditioner or the like is referred to as “individual connection”. In addition, connecting the fuel cell stack group or the stack module in series inside and connecting to the power conditioner or the like is called “collective connection”.

  In addition, when fuel cell stack groups (or stack modules) are connected together, if any one fails, all power generation functions will be cut off, and if a non-generic terminal is taken out, it will fail. A fuel cell stack group (or stack module) that does not exist is also stopped and may be wasted.

  In other words, in a fuel cell system equipped with a fuel cell stack group, there is a trade-off between temperature maintainability in the hot box and versatility of the power connection mode, and the number of terminals to be taken into consideration is determined by setting priority. However, in the prior art including Patent Documents 1 to 3, the priority is not taken into consideration.

  In consideration of the above facts, the present invention can uniquely specify the selection depending on whether priority is given to maintaining the temperature in the hot box or improving the versatility of the output power supply in order to improve power generation efficiency. The object is to obtain a fuel cell system.

In the present invention, a multi-stage fuel cell stack group including at least one stack module that generates power by a chemical reaction between fuel gas and air, and an atmosphere inside the housing are maintained at a predetermined temperature, and hot box that houses the fuel cell stack groups of multi-stage, the pass through the inside and outside of the housing of the hot box, having at least a pair of terminals are connected in correspondence with the fuel cell stack groups of the multi-stage, the For each type determined by the relationship between the versatility of the stack module and the fuel cell stack group and the temperature maintainability in the hot box, the number of sets of the pair of terminals penetrating the inside and outside of the hot box is specified. This is a featured fuel cell system.

  According to the present invention, in the hot box, the atmosphere inside the casing is maintained at a predetermined temperature, and the multistage fuel cell stack group is accommodated in the casing. The hot box is provided with a pair of terminals that are electrically connected to the electrodes of the multi-stage fuel cell stack group, so that wiring can be taken out to the outside.

  At this time, the pair of terminals penetrates the inside and outside of the housing of the hot box and is connected corresponding to the multistage fuel cell stack group.

  By connecting the terminals in this way, for example, the selection based on whether priority is given to maintaining the temperature in the hot box for improving power generation efficiency or versatility of the specifications of the output power supply is uniquely specified. be able to.

  In the present invention, the terminal is not limited to a conductive member that connects an electric cable inside and outside the hot box. For example, the terminal has a structure that penetrates a single electric cable inside and outside the hot box. In this case, the area of the electric cable that passes through the hot box may be defined as a terminal.

  Further, the multi-stage fuel cell stack group of the present invention may be connected in multiple stages so that the downstream fuel cell stack group receives the regenerated fuel gas from the upstream fuel cell stack group and generates power. is there. In this configuration, when the fuel cell stack group at each stage includes a plurality of stack modules, it may be an assembly of stack modules that generate power under the same conditions.

  In the present invention, when the fuel cell stack group includes a plurality of electrically independent stack modules, the pair of terminals are connected to each of the plurality of stack modules, and the fuel cell stack group is electrically When a plurality of stack modules connected to each other are included, the pair of terminals are connected to each of the fuel cell stack groups, and the multi-stage fuel cell stack groups are electrically connected to each other. The pair of terminals are connected to one pole of the first stage fuel cell stack group and to the other pole of the last stage fuel cell stack group.

  Appropriate terminals can be provided in the configuration of each fuel cell stack group.

  The present invention further includes a switch that opens or closes the terminals, and the fuel cell stack group is connected collectively or individually by opening and closing the switch.

  By opening or closing the switch, fuel cell stack groups can be connected together or individually, and versatility can be improved.

  In the present invention, it further includes a switch that opens or closes between terminals, and a disconnect control unit that electrically disconnects the stack module by opening and closing the switch.

  By electrically disconnecting the stack module by opening and closing the switch, the stack module can be selected and power generation can be continued.

  The present invention further includes a switch that opens or closes terminals, and a separation control unit that electrically separates each of the multistage fuel cell stack groups by opening and closing the switches.

  By bypassing each fuel cell stack group, it is possible to select the fuel cell stack group and continue power generation.

  In the present invention, the hot box has a trade-off relationship between the temperature maintainability of the hot box atmosphere that varies depending on the number of the terminal groups, and the temperature maintainability. The number of terminal groups may be selected based on the mutual priority of the versatility of the wiring combination that varies depending on the number.

  That is, the temperature maintainability of the hot box atmosphere that varies depending on the number of terminal groups, and the temperature maintainability is a trade-off relationship, and the versatility of wiring combinations that vary depending on the number of terminal groups, The number of terminal groups can be selected based on the mutual priority.

  In the present invention, in the hot box, terminal groups penetrating inside and outside are gathered and embedded, and a detachable connector terminal unit is provided, and the terminal groups of the connector terminal unit are used as the pair of terminals. It is characterized by.

  Since the terminal take-out positions can be integrated, the temperature maintenance characteristics can be improved.

  As described above, in the present invention, it is possible to uniquely specify the selection depending on whether priority is given to maintaining the temperature in the hot box or the versatility of the specifications of the output power supply in order to improve power generation efficiency. Has an excellent effect.

1 is a schematic configuration diagram of a fuel cell system according to an embodiment. It is a front view which shows the structure of the hot box in which the fuel cell stack group which concerns on this Embodiment is accommodated, (A) shows A type, (B) shows B type, (C) shows C type. It is a front view which shows the structure of the hot box in which the fuel cell stack group which concerns on this Embodiment is accommodated, (A) shows D type, (B) shows E type, (C) shows F type. It is a front view which shows the structure of the hot box in which the fuel cell stack group which concerns on this Embodiment is accommodated, (A) shows G type, (B) shows H type, (C) shows I type. (A) Distribution diagram showing the form of versatility-temperature maintenance in the structure type of the hot box according to the present embodiment, and (B) is a chart showing the outline of the structure type of the hot box. It is a flowchart which shows the failure diagnosis control routine performed with the control part of this Embodiment. It is a front view which shows the structure (J type) of the hot box in which the fuel cell stack group which concerns on this Embodiment which concerns on a modification is accommodated.

  The configuration of the fuel cell system 10 according to the present embodiment will be described together with the functions of the respective parts according to FIG. The fuel cell system 10 of the present embodiment is an example, and the structure may be appropriately modified (including expansion and removal) in each part, but the basic concept of generating power does not change.

  The fuel cell system 10 mainly includes a vaporizer 12, a reformer 14, a first fuel cell stack 16 and a second fuel cell stack 18 as a fuel cell stack group, an air supply unit 46, a separation unit 20, 1 heat exchange part 30, 2nd heat exchange part 32, 3rd heat exchange part 34, 4th heat exchange part 36, combustor 40, tank 42, and control part 44 are provided.

  The first fuel cell stack 16 is a solid oxide fuel cell stack, and has a plurality of stacked fuel cells. The first fuel cell stack 16 may include a plurality of stack modules 16M1, M2,... Mn “n is a positive integer” (see FIG. 2) that receives fuel gas and air under the same conditions.

  The second fuel cell stack 18 is a solid oxide fuel cell stack, and has a plurality of stacked fuel cells. The second fuel cell stack 18 may include a plurality of stack modules 18M1, M2,... Mn “n is a positive integer” (see FIG. 2) that receives fuel gas and air under the same conditions.

  That is, the fuel cell system 10 according to the present embodiment has a multi-stage fuel cell system in which the fuel cell stack has a plurality of stages (here, the first fuel cell stack 16 and the second fuel cell stack 18). 10 is constituted. Note that the number of stages is not limited to two, and may be three or more. Note that air may be received under the same conditions in each stage.

  One end of the source gas pipe P1 is connected to the vaporizer 12, and the other end of the source gas pipe P1 is connected to a gas source (not shown). A gas (for example, methane) is sent from the gas source to the vaporizer 12 by the blower B. A water supply pipe P2 from a tank 42 for storing water is connected to an intermediate portion of the source gas pipe P1. Water (liquid phase) is sent from the tank 42 to the vaporizer 12 by the pump P.

  In the vaporizer 12, water is vaporized. For the vaporization, the heat of the combustor 40 described later is used. In this embodiment, methane is used as the raw material gas, but it is not particularly limited as long as it can be reformed, and a hydrocarbon fuel can be used. Examples of the hydrocarbon fuel include natural gas, LP gas (liquefied petroleum gas), coal reformed gas, biogas, and lower hydrocarbon gas.

  In the vaporizer 12, the supplied methane and water are mixed, and heat is obtained from the combustion exhaust gas G6 flowing through the combustion exhaust pipe P10, and the water is vaporized to become water vapor.

  Methane and water vapor are sent from the vaporizer 12 to the reformer 14 via the pipe P3. In the reformer 14, a fuel gas G1 containing about 600 ° C. containing hydrogen is generated by the reforming reaction. The fuel gas G1 is supplied to the anode 16A of the first fuel cell stack 16 via the fuel gas pipe P4.

  At the cathode 16B of the first fuel cell stack 16, the permeated portion exhaust gas (mixed gas of air A, carbon dioxide, and water vapor) discharged from the permeated portion 26 of the separation portion 20 passes through the oxidizing gas pipe P5 as the oxidizing gas G5. It is supplied via. Thereby, in the 1st fuel cell stack 16, electric power generation is performed by a chemical reaction.

  The first fuel cell stack 16 generates heat by the chemical reaction, and power generation is performed at a temperature of about 650 ° C. Along with this power generation, the anode off gas G3 is discharged from the anode 16A of the fuel cell stack 16. Further, the cathode off gas G2 is discharged from the cathode 16B, and the cathode off gas G2 is supplied to the cathode 18B of the second fuel cell stack 18 through the cathode off gas pipe P6.

  The anode off-gas G3 discharged from the anode 16A is guided to the anode off-gas pipe P7, and flows into the inflow section 24 of the separation section 20 through the second heat exchange section 32 and the first heat exchange section 30. In the second heat exchange unit 32, the temperature of the anode off gas G3 is reduced to some extent from about 650 ° C. (a decrease of about 80 ° C. to 140 ° C.), and in the first heat exchange unit 30, the temperature of the anode off gas G3 is The temperature is lowered to a temperature close to the appropriate temperature T0.

  On the other hand, from the air supply unit 46, the air A whose flow rate is controlled by feedback control of the temperature T of the separation unit 20 by the control unit 44 is separated from the air supply pipe P8 via the first heat exchange unit 30. Are transmitted to the transmission unit 26. In the first heat exchange unit 30, the temperature of the air A is a temperature close to the appropriate temperature T0, that is, substantially the same temperature as the anode offgas G3 after the heat exchange is performed in the first heat exchange unit 30.

  The anode off gas G3 flows into the inflow part 24 of the separation part 20 through heat exchange in the second heat exchange part 32 and the first heat exchange part 30, and at least one of carbon dioxide and water vapor passes through the separation membrane 28. Then, it is separated by moving to the transmission part 26 side.

  The regenerated fuel gas G4 is sent out from the inflow section 24, and is heated to about 600 ° C. through the fourth heat exchange section 36 and the second heat exchange section 32, and the regenerated fuel gas pipe P9 causes the second fuel cell stack 18 to Supplied to the anode 18A. In the second fuel cell stack 18, power generation is performed by a chemical reaction.

  The second fuel cell stack 18 generates heat due to the chemical reaction, and power is generated at a temperature of about 650 ° C. Spent gas at the anode 18A and the cathode 18B is sent to the combustor 40 through the pipe P11 and the cathode off combustion introduction pipe P12, and is burned by the combustor 40.

  The combustion exhaust gas G6 from the combustor 40 passes through the third heat exchange unit 34, the fourth heat exchange unit 36, and the vaporizer 12, and is sent to the tank 42 through the combustion exhaust gas pipe P10. The water vapor contained in the combustion exhaust gas G6 is cooled in the path from the vaporizer 12 to the tank 42 or in the tank 42, condensed, and stored in the tank 42. Other combustion exhaust gas is discharged from the tank 42 to the outside of the apparatus.

  On the other hand, the air A as the sweep gas that has flowed into the permeation section 26, together with the carbon dioxide and water vapor that have permeated through the separation membrane 28 and the gas in the anode off-gas G3 that has permeated through the separation membrane 28, is transmitted through the permeation section 26. Is sent from.

  The transmitted permeated portion exhaust gas G7 is supplied to the cathode 16B through the third heat exchanging portion 34 as the oxidizing gas G5 through the oxidizing gas pipe P5.

  (Insulation of fuel cell stack)

  As shown in FIGS. 2 to 4, most devices including the first fuel cell stack 16 and the second fuel cell stack 18 of the present embodiment (except for the separation unit 24 and the tank 42 in the case of FIG. 1). ) Is accommodated in the hot box 50.

  The hot box 50 has a casing 50A mainly formed of a heat insulating material. The first fuel cell stack 16 and the second fuel cell stack 18 accommodated in the casing 50A have an atmosphere 50B separated from the outside air. It is maintained at a predetermined temperature (including a predetermined allowable range) under the environment.

  By the way, the 1st fuel cell stack 16 and the 2nd fuel cell stack 18 are comprised by several stack module 16M1, M2 ... Mn, and 18M1, M2 ... Mn (n is a positive integer), respectively. . In other words, each of 16M1, M2... Mn, and each of 18M1, M2... Mn has an anode (positive electrode) and a cathode (negative electrode), and is appropriately electrically connected to output a predetermined voltage. can do.

  As for the output voltage, at least one of the voltage and the current is controlled by a power conditioner or the like constituting a part of the control unit 44 (see FIG. 1), and is output as a power source.

  However, the power generated by the first fuel cell stack 16 and the second fuel cell stack 18, including the fuel cell system 10 of the present embodiment, is used as any power source specification (at least one of voltage or current, capacity, etc.) ) Depends on demand and cannot be specified in general. Therefore, in order to have versatility, the anode and the minus from the hot box 50 are provided for each of the finely classified units (that is, the stack modules 16M1, M2... Mn and the stack modules 18M1, M2... Mn). It is preferable to take out the pole.

  On the other hand, it is important for maintaining the power generation capability that the first fuel cell stack 16 and the second fuel cell stack 18 are maintained by the hot box 50 under a substantially constant atmospheric temperature. Is preferably less. That is, in the fuel cell system 10 of the present embodiment (in the multi-stage type, since the temperature obtained by the combustor 40 is small, in the hot box 50, the element that allows heat to escape (the number of terminals that cause the temperature decrease) is the minimum necessary. It is desirable to reduce it to the limit.

  That is, versatility and temperature maintainability are in a trade-off relationship, and the number of terminals taken out from the hot box 50 varies depending on the priority setting. In other words, the first fuel cell stack 16 and the second fuel cell stack (16M1, M2,... Mn, and 18M1 in and out of the hot box 50 are used depending on whether generality is given priority or temperature maintenance is given priority. , M2... Including Mn), it is important to prepare a wiring structure according to priority in advance.

  Therefore, in the present embodiment, as shown in FIG. 5, the number of terminals output from the hot box 50 (in terms of the structure, the hot box 50 in accordance with the respective advantages in the relationship between versatility and temperature maintainability. By classifying the configuration of the number of through holes), the number of terminals output from the hot box 50 can be uniquely specified based on the priority to be set.

  In the present embodiment, the hot box 50, the first fuel cell stack 16 and the second fuel cell stack 18, and the plurality of stack modules 16M1, M2... Mn, and 18M1, M2. Nine types (A type to I type shown in FIG. 5 (B)) are set as variations in the connection state of the electrodes (positive electrode, negative electrode), and as shown in FIG. 5 (A), Were distributed in a chart with versatility on the horizontal axis and temperature maintainability on the vertical axis.

  2 to 4 are conceptual diagrams showing the structure of each type (A type to I type) hot box 50.

  The hot box 50 accommodates the first fuel cell stack 16 and the second fuel cell stack 18, and is maintained at the atmospheric temperature in the hot box 50.

  (A type)

  As shown in FIG. 2A, the A type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 16M1, M2... Mn of the second fuel cell stack 18. 18M1, M2,... Mn, the positive terminal 50C and the negative terminal 50C are taken out to the outside through the terminal 50C provided in the hot box 50. In this state, each is an independent connection. The extracted terminal 50C can be in various connection states (collective connection or individual connection). Also, selection can be made in the smallest unit.

  As shown in FIG. 2A, the A type has high versatility because the terminals 50C are taken out in the smallest unit, and is distributed at positions where the temperature maintainability is low because the number of terminals 50C is the largest (see FIG. 2A). (Refer to point A in 5 (A)).

  (B type)

  As shown in FIG. 2B, the B type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 16M1, M2. 18M1, M2,... Mn, the positive terminal 50C and the negative terminal 50C are taken out to the outside through the terminal 50C provided in the hot box 50.

  The stack modules 16M1, M2,... Mn of the first fuel cell stack 16 taken out to the outside are all connected together.

  Also, 16M1, M2,... Mn of the second fuel cell stack 18 taken out to the outside are connected together in a lump.

  That is, in the B type, the first fuel cell stack 16 and the second fuel cell stack 18 are output in an independent form (for each number of fuel cell stack stages).

  As shown in FIG. 2B, the B type has the same temperature maintainability as the A type, but is basically already connected in units of the first fuel cell stack 16 and the second fuel cell stack 18. For this reason, it is distributed at positions that are slightly less versatile than the A type (see point B in FIG. 5A).

  (C type)

  As shown in FIG. 2C, the C type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 16M1, M2... Mn of the second fuel cell stack 18. 18M1, M2,... Mn, the positive terminal 50C and the negative terminal 50C are taken out to the outside through the terminal 50C provided in the hot box 50.

  The stack modules 16M1, M2,... Mn of the first fuel cell stack 16 taken out to the outside and the stack modules 18M1, M2,.

  That is, the C type is output in a form in which the first fuel cell stack 16 and the second fuel cell stack 18 are integrated (all stacks are collectively connected).

  As shown in FIG. 2C, the C type has the same temperature maintainability as the A type and B type, but basically all the stacks (the first fuel cell stack 16 and the second fuel cell stack 18). ) Is already in a collective connection state, and is therefore distributed at positions that are slightly less versatile than the B type (see point C in FIG. 5A).

  The A type, the B type, and the C type have a structure in which the terminal 50C is output independently from the individual stack modules 16M1, M2... Mn and 18M1, M2. The distribution positions in FIG. 5A may be the same because the difference in versatility is in a negligible range.

  (D type)

  As shown in FIG. 3A, each of the D type includes stack modules 16M1, M2... Mn of the first fuel cell stack 16, and stack modules 18M1, M2. Are connected together in the hot box 40, and the first fuel cell stack 16 and the second fuel cell stack 18 are independently connected to each other via a terminal 50C with a pair of electrodes (a positive electrode and a negative electrode). Has been taken out.

  In the case of this D type, in the present embodiment, since the number of fuel cell stacks is two, that is, the first fuel cell stack 16 and the second fuel cell stack 18, the number of terminals 50C is four (fuel) Battery stack x 2).

  As shown in FIG. 3 (A), the D type is a state in which the first fuel cell stack 16 and the second fuel cell stack 18 are independently connected, and the A type to the F type have both temperature maintenance and versatility. Are averaged and distributed at the origin position (see point D in FIG. 5A). In other words, for the evaluation of the temperature maintenance property and the versatility, the evaluations of A type to C type, E type, and F type are set based on the D type.

  (E type)

  As shown in FIG. 3B, the E type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 18M1, M2. However, the first fuel cell stack 16 and the second fuel cell stack 18 are independently connected to each other with a pair of electrodes (a positive electrode and a negative electrode) taken out through the terminal 50C. .

  Further, the first fuel cell stack 16 and the second fuel cell stack 18 taken out to the outside are connected together.

  In the case of this E type, in the present embodiment, since the number of fuel cell stacks is two, that is, the first fuel cell stack 16 and the second fuel cell stack 18 as in the D type, the number of terminals 50C is 4 (fuel cell stack x 2).

  As shown in FIG. 3B, in the E type, the first fuel cell stack 16 and the second fuel cell stack 18 are in a collective connection state, and the temperature maintainability is average, but slightly higher than the D type. It is distributed at positions where versatility is reduced (see point D in FIG. 5A).

  The D type and E type can be classified as one group (second group) in the structure in which the terminal 50C is output in units of fuel cell stacks, and the difference in versatility is in a negligible range. The distribution positions in FIG. 5A may be the same.

  (F type)

  As shown in FIG. 3C, the F type includes stack modules 16M1, M2... Mn of the first fuel cell stack 16, and stack modules 18M1, M2. However, the first fuel cell stack 16 and the second fuel cell stack 18 are collectively connected in the hot box 40.

  That is, one electrode (for example, negative electrode) of the first fuel cell stack 16 and the second fuel cell stack 18 and one electrode (for example, positive electrode) of the second fuel cell stack 18 are within the hot box 50. The other electrode (for example, the positive electrode) of the first fuel cell stack 16 and the other electrode (for example, the negative electrode) of the second fuel cell stack 18 are respectively connected to the terminal 50C. Through the hot box 50. That is, the minimum number of the two terminals 50C is the highest in temperature maintainability but distributed at the lowest versatility (see point F in FIG. 5A).

  The following three types of G type, H type, and I type are positioned as additional functions of the A type to the F type, unlike the classification of the six types of the A type to the F type.

(G type)

  As shown in FIG. 4A, the G type includes stack modules 16M1, M2... Mn of the first fuel cell stack 16, and stack modules 18M1, M2. The positive electrode terminal 50 </ b> C and the negative electrode terminal 50 </ b> C are taken out through a single connector terminal 50 </ b> C provided in the hot box 50. However, the terminals are insulated from each other in a single connexer terminal, and are not short-circuited.

  As shown in FIG. 4A, in the G type, the connector terminal 50C is taken out in the minimum unit, but when the connector terminal 50C is used, it is not necessary to be in the minimum unit, and all types (A type to F type). For example, in the case of the E type, four lines are collected. Further, the connector terminal 50C is not limited to one place, and a plurality of connector terminals 50C in which a plurality of wires are bundled may be provided. Furthermore, the positive pole and the negative pole may be separated.

  (H type)

  As shown in FIG. 4B, the H type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 18M1, M2. Are connected to each other inside the hot box 50, and a pair of electrodes (a positive electrode and a negative electrode) of the first fuel cell stack 16 and the second fuel cell stack 18 are connected via the terminal 50C. It has been taken out to the outside (so far, an example of the same configuration as the E type has been shown).

  In the H type, one electrode (for example, a negative electrode) of the first fuel cell stack 16 and one electrode (for example, a positive electrode) of the second fuel cell stack 18 are outside the hot box 50. Connection is made via a switch 52.

  That is, in the H type, the batch connection or individual connection of the fuel cell stack groups at each stage can be selected by the closing or opening control of the switch 52 outside the hot box 50. Such a configuration in which the wiring taken out of the hot box 50 is provided with a switch switching function is applicable to the A type to E type.

  (I type)

  As shown in FIG. 4C, the I type includes the stack modules 16M1, M2... Mn of the first fuel cell stack 16, and the stack modules 18M1, M2. The positive electrode terminal 50 </ b> C and the negative electrode terminal 50 </ b> C are taken out to the outside through the terminals 50 </ b> C provided in the hot box 50. In this state, each is an independent connection, but the extracted terminal 50C can be in various connection states (collective connection or individual connection). Also, selection can be made in the smallest unit.

  Here, the I type is a first switch that conducts between the electrodes of the stack modules 16M1, M2... Mn of the first fuel cell stack 16 and the stack modules 18M1, M2. 54, and a second switch 56 interposed in at least one of the respective electrodes.

  Accordingly, as shown in FIG. 4C, when any one of the stack modules 16M1, M2... Mn and 18M1, M2. With the opening and closing control, the faulty stack module can be electrically disconnected (see the dotted line in FIG. 4C), and the unique effect of effectively using another stack module that is operating normally Can be obtained.

  As shown in FIG. 5A, A type to F type can be classified according to temperature maintainability and versatility, but can be differentiated from the viewpoint of efficiency when boosting voltage with a power conditioner or the like. . The efficiency is higher when the voltage applied to the power condition or the like is higher, that is, when the number of output terminals is smaller. Therefore, the C type, E type, and F type are the most efficient. Next, B type and E type are the next most efficient after C type, D type, and F type. The A type has the lowest efficiency in terms of efficiency.

  Moreover, the G type as an additional function can improve temperature maintenance property as an effect. The H type as an additional function can improve versatility. In addition, Type I can isolate the faulty module and minimize the loss of the fuel cell system.

  The operation of the present embodiment will be described below.

  (Power generation operation of multi-stage fuel cell stack)

  In the fuel cell system according to the present embodiment, first, methane is supplied from a gas source and water is supplied to the vaporizer 12 for the first fuel cell stack as the first stage. The supplied methane and water are mixed and heated by obtaining heat from the combustion exhaust gas, and the water is vaporized to become steam.

  Methane and water vapor are sent from the vaporizer 12 to the reformer 14. In the reformer 14, a fuel gas G1 containing about 600 ° C. containing hydrogen is generated by the reforming reaction. The fuel gas G1 is supplied to the anode 16A of the first fuel cell stack 16. An oxidizing gas G5 is supplied to the cathode 16B of the first fuel cell stack 16. Thereby, in the 1st fuel cell stack 16, electric power generation is performed by a chemical reaction.

  Along with this power generation, the anode off gas G3 is discharged from the anode 16A of the fuel cell stack 16. Further, the cathode off gas G2 is discharged from the cathode 16B, and the cathode off gas G2 is supplied to the cathode 18B of the second fuel cell stack 18.

  The anode off gas G3 discharged from the anode 16A flows into the inflow section 24 of the separation section 20, and at least one of carbon dioxide and water vapor is separated by passing through the separation membrane 28 and moving toward the permeation section 26. .

  On the other hand, air A is sent from the air supply unit 46 to the transmission unit 26 of the separation unit 20.

  The regenerated fuel gas G4 is sent from the inflow portion 24 and supplied to the anode 18A of the second fuel cell stack 18. In the second fuel cell stack 18, power generation is performed by a chemical reaction.

  The first fuel cell stack 16 and the second fuel cell stack 18 are accommodated in the hot box 50 and maintained under an atmospheric temperature (including a predetermined allowable range) separated from the outside air. By maintaining this temperature, the power generation efficiency can be stabilized in an optimum state.

  Here, in the present embodiment, the specifications of the power source (at least one of voltage or current, capacity, etc.) for the power generated by the first fuel cell stack 16 and the second fuel cell stack 18 are determined. As shown in FIG. 5A, the number of terminals output from the hot box 50 can be uniquely specified based on the priorities of versatility and temperature maintainability.

  A designer or user of the fuel cell system 10 of the present embodiment can use a general-purpose for providing variations in the electrode wiring structure of the first fuel cell stack 16 and the second fuel cell stack 18 based on specifications during operation. The temperature and the atmospheric temperature inside the hot box 50 are maintained, and it is determined which of the temperature maintainability for stabilizing the power generation efficiency is prioritized. For example, as shown in FIG. 5 (A), each characteristic is roughly divided into 4 by classifying the characteristic into a plus side (an event where the characteristic is dominant) and an event where the characteristic is negative, with the origin at the center. Set an event.

  Among them, the type corresponding to the determined priority is selected. The selection requirements are listed below.

  (Selection Requirement 1) The temperature maintainability may be low, but if higher versatility is better, type A or type B is selected.

  (Selection requirement 2) Although general versatility may be low, type F is selected when higher temperature maintainability is better.

  (Selection Requirement 3) When both the temperature maintenance property and the versatility may be average, type D or type E is selected.

  (Selection requirement 4) A G type or H type configuration can be applied as an additional function to the selected type.

  (Failure diagnosis)

  In the fuel cell system 10, in particular, the first fuel cell stack 16 and the second fuel cell stack 18 are constituted by a plurality of stack modules 16M1, M2... Mn, and 18M1, M2.

  At this time, if some of the stack modules fail, all power generation functions are lost.

  Therefore, the stack module diagnosed as faulty by fault diagnosis can be electrically disconnected.

  FIG. 6 is a flowchart showing a flow of a failure diagnosis control routine executed in the control unit 44.

  In step 60, fault diagnosis is executed. For example, the voltage (electromotive force) for each stack module is measured to determine whether or not the threshold value is deviated. For voltage measurement, a voltmeter may be installed in the device in advance, and the value measured by the inspector using the inspection machine regularly or irregularly may be input manually or automatically to the input part of the fault diagnosis control. May be. Further, the voltage measurement may be performed when the apparatus is not in operation.

  In the next step 62, it is determined whether or not there is a stack module that has failed as a result of the failure diagnosis in step 60.

  If a negative determination is made in step 62, it is determined that there is no failed stack module, and this routine ends.

  If the determination in step 62 is affirmative, it is determined that a faulty stack module is present, the process proceeds to step 64, the faulty stack module is specified, and the process proceeds to step 66.

  In step 66, the switching state of the first switch 54 and the second switch 56 is set for avoiding (electrically disconnecting) the specified stack module from other stack modules. 68.

  In step 68, the switching process of the first switch 54 and the second switch 56 is executed based on the switching state set in step 66, and the process proceeds to step 70.

  As a result, as indicated by the dotted line in FIG. 4C, it is possible to flow the current by avoiding the stack module in which the current has failed, and even if some stack modules fail, the electromotive force is generated in the other stack modules. Can be obtained.

  In step 70, adjustment of at least one of voltage or current (such as adjustment of at least one of converter voltage or current) is performed by a power conditioner or the like based on a voltage change caused by electrically disconnecting some of the stack modules. This routine ends.

  As described above, according to the present invention, in the multistage fuel cell system 10, the fuel cell stacks (here, the first fuel cell stack 16 and the second fuel cell stack 18) of each stage are accommodated in the hot box 50. Therefore, the power generation capacity is stabilized by maintaining it in an environment of a predetermined atmospheric temperature.

  On the other hand, the specifications of the power source (at least one of voltage or current, capacity, etc.) as the power generated by the first fuel cell stack 16 and the second fuel cell stack 18 vary depending on demand, It cannot be specified in general. Therefore, in the present embodiment, in the relationship between the versatility of the specifications as a power source and the temperature maintainability, the priority to be set is classified by classifying the configuration of the number of terminals output from the hot box 50 according to the respective advantages. Based on the degree, the number of terminals output from the hot box 50 can be uniquely specified. Thereby, the fuel cell system 10 which maintained the versatility and temperature maintenance property which a user requires can be constructed | assembled.

  In the present embodiment, the first fuel cell stack 16 and the second fuel cell stack 18, and the electrodes provided on the plurality of stack modules 16M1, M2... Mn, and 18M1, M2. (Types of positive and negative poles) and combinations of the number of terminals and the number of terminals are illustrated as A type to F type and G type to I type, but are not limited to these types, and various types are available. It may be distributed over the events of FIG.

  Moreover, in this Embodiment, although the fuel cell system 10 (refer FIG. 1) provided with the separation part 20 was mentioned as an example, it is not limited to the fuel cell system 10 shown in FIG. Different system configurations, such as the presence or absence of an absorbent material, the presence or absence of condensation of anode gas, and the presence or absence of condensation of exhaust gas.

  Furthermore, in this embodiment, as shown in FIG. 5A, versatility and temperature maintainability are set as evaluation items, and the hot box is set according to the respective advantages in the versatility and temperature maintainability relationship. Although the configuration of 50 through holes is classified, the number of parts may be included as an evaluation item. For example, as the number of terminals increases, for example, components for boosting the voltage are required, leading to an increase in cost. When the evaluation item is 3 or more, it is preferable to generate each type of radar chart instead of the characteristic diagram of FIG.

  (Modification)

  In the above-mentioned I type (see FIG. 4C), when one of some stack modules 16M1, M2... Mn and 18M1, M2. According to the opening and closing control 54, the failed stack module is electrically disconnected, and the other stack modules that are operating normally are used effectively. However, as shown in FIG. As an example, the separation may be performed in units of fuel cell stack groups (referred to as J type).

  As shown in FIG. 7, in the J type configuration, the first contacts a of the third switches 55A, 55B, 55C, and 55D are connected to the wirings connected to the terminals 50C, respectively. Further, between the electrodes of each fuel cell stack group, fourth switches 57A and 57B are interposed on the second contact side b of the third switches 55A, 55B, 55C and 55D.

  The electrode 16R of one polarity of the first fuel cell stack 16 and the electrode 18L of the other polarity of the second fuel cell stack 18 are turned on when the two third switches 55B and 55C in the center of FIG. Conduction is possible.

  Here, FIG. 7 illustrates a state in which the first fuel cell stack 16 is disconnected and the operation is performed only with the second fuel stack 18. It should be noted that the second fuel cell stack 18 can be disconnected and operated with only the first fuel stack 16 by switching each of the third switch 55 and the fourth switch 57 on and off.

  Of course, not only the first fuel cell stack 16 and the second fuel cell stack 18, but also when there are three or more fuel cell stacks, they can be separated individually. In the failure diagnosis control, the stack module in FIG. 6 may be read as a fuel cell stack, and switching of the third switch 55 and the fourth switch 57 may be controlled as appropriate.

  In addition, here, the case of a failure in the stack module or fuel cell stack group has been described. However, not only in the case of a failure, but if there is a situation where it is not desired to energize each stack module or fuel cell stack group, the same applies. It may be separated by means.

A Air P Pump P1 Raw material gas pipe P2 Water supply pipe P3 pipe P4 Fuel gas pipe P5 Oxidation gas pipe P6 Cathode off-gas pipe P7 Anode off-gas pipe P8 Air supply pipe P9 Regenerated fuel gas pipe P10 Combustion exhaust pipe P11 Pipe P12 Cathode off combustion introduction Tube G1 Fuel gas G2 Cathode off gas G3 Anode off gas G4 Regenerated fuel gas G5 Oxidized gas G6 Combustion exhaust gas G7 Permeate exhaust gas 10 Fuel cell system 12 Vaporizer 14 Reformer 16 First fuel cell stack 16A Anode 16B Cathode 16M1, M2 ..Mn stack module 18 second fuel cell stack 18A anode 18B cathode 18M1, M2... Mn stack module 20 separation section 24 inflow section 26 permeation section 28 separation membrane 30 first heat exchange section 32 second heat exchange Part 34 Third heat exchange part 36 Fourth heat exchange part 40 Combustor 42 Tank 44 Control part 46 Air supply part 50 Hot box 50A Housing 50B Atmosphere 50C Terminal 52 Switch 54 First switch 56 Second switch 55A, 55B, 55C , 55D 3rd switch 57A, 57B 4th switch

Claims (6)

A multi-stage fuel cell stack group including at least one stack module that generates electric power by a chemical reaction between fuel gas and air;
A hot box in which the atmosphere inside the housing is maintained at a predetermined temperature, and the multi-stage fuel cell stack group is housed in the housing;
Having at least a pair of terminals penetrating the inside and outside of the housing of the hot box and connected corresponding to the multi-stage fuel cell stack group ,
The number of sets of the pair of terminals penetrating the inside and outside of the hot box is specified for each type determined by the relationship between the versatility of the stack module and the fuel cell stack group and the temperature maintenance property in the hot box. A fuel cell system. When the fuel cell stack group includes a plurality of electrically independent stack modules, the pair of terminals are connected to each of the plurality of stack modules,
When the fuel cell stack group includes a plurality of stack modules electrically connected to each other, the pair of terminals are connected to each of the fuel cell stack groups,
When the multi-stage fuel cell stack group is electrically connected to each other, the pair of terminals are connected to one pole of the first-stage fuel cell stack group and the other of the last-stage fuel cell stack group Connected to the poles of the
The fuel cell system according to claim 1. A switch that opens or closes the terminals;
3. The fuel cell system according to claim 1, wherein the fuel cell stack groups are connected together or individually by opening and closing the switch. 4. A switch that opens or closes the terminals;
Disconnect control means for electrically disconnecting the stack module by opening and closing the switch;
The fuel cell system according to claim 1 or 2, further comprising: A switch that opens or closes the terminals;
Disconnect control means for electrically disconnecting each of the multi-stage fuel cell stack group by opening and closing the switch;
The fuel cell system according to claim 1 or 2, further comprising:   In the hot box, a terminal group penetrating inside and outside is gathered and embedded, and a detachable connector terminal unit is provided, and the terminal group of the connector terminal unit is used as the pair of terminals. The fuel cell system according to any one of claims 1 to 5.