JP4220925B2 - Fuel cell power generation system - Google Patents

Description

  The present invention relates to a fuel cell power generation system.

  Conventionally, in a fuel cell power generation system, fuel gas is supplied from the fuel gas passage to the fuel electrode of the fuel cell, and oxidant gas is supplied from the oxidant gas passage to the oxidant electrode of the fuel cell. In a fuel cell, water is generated at the oxidant electrode of the fuel cell with a power generation reaction. If generated water accumulates at the oxidant electrode of the fuel cell, the flow of the oxidant gas may be hindered, and power generation efficiency may be reduced. The fact that the generated water hinders the flow of gas inside the fuel cell is called flooding. When the flooding phenomenon occurs, the fuel cell voltage drops rapidly and suddenly.

  Therefore, in order to suppress flooding, Patent Document 1 discloses a fuel cell power generation system provided with a humidification bypass line that bypasses a humidifier and supplies oxidant gas to the fuel cell. When the generated water accumulates in the oxidant electrode of the fuel cell and the power generation efficiency decreases, air is supplied to the oxidant electrode of the fuel cell via the humidifier and air is supplied via the humidification bypass line during operation. In other words, the water supplied to the oxidant electrode of the fuel cell without passing through the humidifier is forced to flow downstream in the operation during operation.

  In Patent Document 2, in a start-up method in which a fuel gas to which water is added is supplied to the anode side and an oxidant gas is supplied to the cathode side, water is added to the fuel gas when it is determined that the voltage is not higher than a set voltage. An activation method is disclosed in which a hydration control step for starting addition of water to the fuel gas is executed when it is determined that the voltage is equal to or higher than the set voltage. This will eliminate the water in the channel.

Patent Document 3 discloses a fuel cell system that supplies dry oxygen to an oxygen electrode and dry hydrogen to a fuel electrode after stopping normal operation.
JP 2000-306595 A JP-A-8-315843 JP 2002-208421 A

  According to the above-described conventional technology, although the flooding phenomenon can be suppressed to some extent, the wet state inside the fuel cell changes depending on the state of the previous operation of the fuel cell and the state of the fuel cell after the previous operation stop. Therefore, simply supplying gas to the inside of the fuel cell has a limit in suppressing the flooding phenomenon, and there is a limit in improving the power generation efficiency. Further, depending on the history of the previous operation of the fuel cell, the voltage may drop immediately after the operation is started. In this case, there is no time margin for determining the wet state inside the fuel cell.

The present invention has been made in view of the above-described circumstances, and when starting the operation of the fuel cell, it is advantageous to suppress the flooding phenomenon from the beginning of the operation and is advantageous to increase the power generation efficiency. It is an object to provide a power generation system.

A fuel cell power generation system according to aspect 1 includes a fuel cell having an electrolyte membrane and a fuel electrode and an oxidant electrode sandwiching the electrolyte membrane, an oxidant gas passage for supplying an oxidant gas to the oxidant electrode of the fuel cell, a fuel cell In a fuel cell power generation system, comprising a fuel gas passage for supplying fuel gas to the fuel electrode of the battery, and adjusting the moisture inside the fuel cell by supplying gas into the fuel cell before load feeding
When starting the fuel cell operation,
At least one of the moisture state inside the fuel cell during the previous operation, the moisture state inside the fuel cell at the end of the previous operation, and the humidity state of the surrounding environment of the fuel cell after the previous operation stop According to the progress history before starting the fuel cell ,
It has a moisture adjustment means for performing a moisture adjustment process for starting to dry the inside of the fuel cell with the gas supplied to the inside of the fuel cell. A load means what is driven by a fuel cell.

In this case, when starting the operation of the fuel cell, the humidity state inside the fuel cell during the previous operation, the moisture state inside the fuel cell at the end of the previous operation, and the surrounding environment of the fuel cell after the previous operation stop A moisture adjustment process for drying the inside of the fuel cell with the gas supplied to the fuel cell is executed in accordance with the history of the progress before the start of the fuel cell consisting of at least one of the humidity states .

  Here, when the moisture history inside the fuel cell is relatively high, in the moisture adjustment process, the drying power (generally, the gas flow rate) of the gas supplied to the fuel cell is relatively set. Can be increased. On the other hand, when the moisture history inside the fuel cell is relatively low, in the moisture adjustment process, the drying power (generally, the gas flow rate) of the gas supplied to the fuel cell is set. It can be reduced relatively. As a result, when starting fuel cell operation, the moisture inside the fuel cell is good from the beginning of operation, regardless of the history before the start of fuel cell startup, and flooding is suppressed from the beginning of operation. Is done. For this reason, the operation can be satisfactorily performed from the beginning of the operation of the fuel cell.

According to the fuel cell power generation system according to aspect 2, in addition to the above-described features, a reformer that reforms the reforming raw material to generate fuel gas is provided, and when the operation of the fuel cell is started, The moisture adjustment means is characterized in that the moisture adjustment process for start is executed in a time-overlapping manner during the start- up operation of the reformer. In this case, when the operation of the fuel cell is started, the moisture adjustment means performs the moisture adjustment process for the start in time overlap with the start- up operation of the reformer. Accordingly, a moisture adjustment process for starting is executed in parallel with the start- up operation of the reformer. Therefore, it is possible to prevent the rise time of the fuel cell from being prolonged. Further, since a carrier such as a blower, a fan, or a compressor that supplies gas to the inside of the fuel cell in the moisture adjustment process is driven in the reforming process, an operation noise is often generated. On the other hand, the operation sound of the reformer is generated even during the start-up operation of the reformer. Therefore, the generation time of the operation sound in the moisture adjustment process for start and the generation time of the operation sound of the reformer can be overlapped in time, and the generation time of the operation sound can be prevented from being prolonged. .

According to the fuel cell power generation system according to aspect 3, in addition to the features described above, and the purge processing unit is provided for supplying purge gas to the reformer when exiting the operation of the fuel cell, starts the operation of the fuel cell to time, the the moisture adjusting unit to execute the moisture adjustment process for starting, when to end the operation of the fuel cell, humidity adjusting means, the purge process for supplying purge gas to the reformer by the purge gas processing unit It is characterized in that a moisture adjustment process for termination is performed in which the inside of the fuel cell is dried with the gas supplied into the inside of the fuel cell in a time-overlapping manner. Thus humidity adjusting means, purge the purge processing temporally overlap to be supplied to the reformer to perform the moisture adjustment process for completion by the purge unit. Therefore, when the operation of the fuel cell is terminated, a moisture adjustment process for termination is executed in parallel with the purge process. In the moisture adjustment process for termination, since a carrier source such as a blower, a fan, and a compressor for supplying gas to the fuel cell is driven in the moisture adjustment process, an operation noise is often generated. On the other hand, even when supplying a purge gas to the reformer by the purge unit, the operation sound of the reformer is generated. Accordingly, the generation time of the operation sound in the moisture adjustment processing for termination and the generation time of the operation sound by the purge processing unit can be overlapped in time, and the generation time of the operation sound can be prevented from being prolonged.

According to the fuel cell power generation system according to aspect 4, in addition to the above-described features, the moisture adjustment means supplies the fuel cell to the moisture adjustment process for starting to adjust the moisture inside the fuel cell. It is characterized by having gas drying power increasing means (gas drying power adjusting means) for increasing the drying power of the gas by adjusting at least one of the temperature, humidity and flow rate of the gas. Thus, if the gas drying power is adjusted by the gas drying power increasing means, the moisture inside the fuel cell can be adjusted. The gas drying power increasing means can adjust at least one of a gas flow rate per unit time, a gas temperature, and a gas humidity. In order to increase the drying power of the gas, the gas flow rate per unit time may be increased or heated.

According to the fuel cell power generation system according to aspect 5, in addition to the above-described features, information on the atmospheric humidity at the end of the previous operation, information on the atmospheric humidity at the start of the current operation, Ambient environment humidity determination means for determining the humidity of the ambient environment of the fuel cell based on at least one of the information on the humidity of the atmosphere from the end to the start of the current operation is provided. When the ambient humidity is determined to be relatively high by the ambient environment humidity determining means, the moisture adjusting means relatively increases the drying power by the gas supplied to the fuel cell, and the ambient humidity is relatively high. When the humidity is determined by the ambient environment humidity determination means, the moisture adjustment means relatively reduces the drying power by the gas supplied to the fuel cell.

During the operation stop of the fuel cell, it is often the internal wetting state of the fuel cell varies depending on the humidity of the surrounding environment. In this case, when the humidity of the surrounding environment is relatively high, the moisture adjusting means relatively increases the drying power by the gas supplied to the inside of the fuel cell. When the humidity of the surrounding environment is relatively low, the moisture adjusting means relatively reduces the drying power by the gas supplied to the inside of the fuel cell. Therefore, even when the wet state inside the fuel cell changes according to the humidity of the surrounding environment, it can be dealt with.

According to the fuel cell power generation system according to aspect 6, in addition to the above-described features, at least one of during the operation of the fuel cell, when the operation of the fuel cell is completed, when the operation of the fuel cell is stopped, and when the operation of the fuel cell is started , characterized in that the determined wet state determining means internal wetting state of the fuel cell is provided.

As described above, the wet state determination means determines the wet state inside the fuel cell. Thus wet state during internal operation of the fuel cell, the inside of the operation at the end of wetting state of the fuel cell, at least one of the inner operation before starting wet state of the fuel cell Ru is estimated.
According to the fuel cell power generation system according to aspect 7, in addition to the above-described features, when the operation of the fuel cell is terminated, the moisture adjusting means is for ending the inside of the fuel cell with the gas supplied to the fuel cell. The moisture adjustment process is executed. Even when the operation of the fuel cell is terminated, the inside of the fuel cell is dried by the gas supplied to the fuel cell.

According to the fuel cell power generation system according to the present invention, when starting the operation of the fuel cell 1, the load power supply previously, according to the elapsed history described above, moisture adjustment means supply gas to the fuel cell Then , the moisture adjustment process for starting to adjust the moisture inside the fuel cell and dry it is executed. As a result, when the operation of the fuel cell is started, the moisture inside the fuel cell can be optimized from the beginning of the operation. As a result, the flooding phenomenon can be suppressed from the beginning of operation, and the fuel cell can be operated satisfactorily.

Examples of the history of the fuel cell before starting the start include, for example, the internal state (humidity state) at the previous operation of the fuel cell, the internal state (humidity state) at the end of the previous operation of the fuel cell, and the fuel Examples include at least one of the states (humidities) of the surrounding environment after the previous stop of the battery.

When referring to the moisture inside the fuel cell during operation, it can be performed, for example, as follows. That is, when the humidity inside the fuel cell during the previous operation is relatively high, it is estimated that the moisture before the start of operation inside the fuel cell is relatively high. The drying power (generally, gas flow rate) of the gas supplied to the inside of the gas generator can be relatively increased.
When a relatively low moisture inside the fuel cell in the previous during operation, because the moisture in the interior of the operation before the start of the fuel cell is estimated to be relatively low, in moisture adjustment process, the fuel cell The drying power (generally gas flow rate) of the gas supplied to the gas can be relatively reduced. A gas preheating means for preheating gas supplied for moisture adjustment can be provided inside the fuel cell. An example of the gas preheating means is a heat exchanger. As a heat exchanger, what is heated with the heat | fever of the waste gas discharged | emitted from reforming systems, such as a combustor for reformers, can be illustrated.

  Furthermore, a fuel cell preheating means for adjusting the moisture inside the fuel cell by preheating the fuel cell from the inside can be provided. As fuel cell preheating means, the fuel cell is warmed from the inside by preheating water flowing through a cooling system that cools the fuel cell during operation of the fuel cell and passing the preheated water into the fuel cell. A method for adjusting the moisture inside the fuel cell can be exemplified.

Further, when referring to the moisture inside the fuel cell at the end of the previous operation, for example, it can be performed as follows. That is, when the humidity inside the fuel cell at the end of the previous operation is relatively high, it is estimated that the moisture before the start of operation inside the fuel cell is relatively high. drying power of the gas supplied into the battery (typically gas flow rate) can be relatively increased. When the humidity inside the fuel cell at the end of the previous operation is relatively low, it is estimated that the moisture before the start of operation inside the fuel cell is relatively low . The drying power (generally, gas flow rate) of the gas supplied to the inside can be relatively reduced.

Furthermore, when referring to the moisture in the surrounding environment (generally the atmospheric state) in which the fuel cell is installed, it can be performed, for example, as follows. That is, when the humidity of the surrounding environment during the shutdown of the fuel cell is relatively high, the drying power of the surrounding environment during the shutdown is relatively low. Therefore, in the moisture adjustment process, it is possible to relatively increase the drying power (generally, gas flow rate) of the gas supplied to the fuel cell. In addition, when the humidity of the surrounding environment (generally the atmospheric state) is relatively low when the fuel cell is stopped, the drying power of the surrounding environment is relatively high when the operation is stopped. The humidity inside the fuel cell is estimated to be relatively low in the fuel cell. Therefore, in the moisture adjustment process, the drying power (generally, the gas flow rate) of the gas supplied to the inside of the fuel cell is relatively reduced. Can do. Note that reducing the drying power of the gas includes setting the flow rate of the drying gas supplied to the fuel cell to zero.

  EMBODIMENT OF THE INVENTION The form for inventing is demonstrated below based on each Example.

  FIG. 1 illustrates a first embodiment. The fuel cell power generation system includes a stack 13 in which a plurality of fuel cells 1 having an electrolyte membrane and a fuel electrode and an oxidant electrode sandwiching the electrolyte membrane are stacked, and an oxidant that supplies an oxidant gas to the oxidant electrode of the fuel cell 1. It has a gas passage 2, a fuel gas passage 3 that supplies fuel gas to the fuel electrode of the fuel cell 1, and a control device 7 that controls the operation of the fuel cell 1.

  As shown in FIG. 1, the fuel gas passage 3 includes an outlet 4 a of the reforming system 4, an inlet valve 30, an outward path 3 a toward the inlet 1 a of the fuel path of the fuel cell 1, an outlet 1 b of the fuel path of the fuel cell 1, And a return path 3b that reaches the inlet 43a of the reformer combustor 43 via the outlet valve 33 and the first off-gas valve 34. A bypass passage 35 and a bypass valve 36 that bypass the fuel cell 1 are provided between the forward path 3a and the return path 3b.

  The reforming system 4 includes a reformer 40 that generates a reformed raw material as a fuel gas, a passage 41 that supplies the reformed raw material to the reformer 40, and a passage that supplies raw water serving as steam to the reformer 40. 42, a reformer combustor 43 that maintains the reformer 40 at a high temperature, and a blower 45 (air supply source) that supplies combustible gas to the reformer combustor 43 through the filter 44.

  As shown in FIG. 1, the return path 3 b of the fuel gas passage 3 is connected to an offgas combustor 38 via a second offgas valve 37. When the air blower 39 (air supply source) is activated, air is supplied to the off-gas combustor 38, and combustion in the off-gas combustor 38 is favorably performed. The heat exchanger 6 heated by the heat of the exhaust gas discharged from the off-gas combustor 38 has a water circulation in which water circulates through the cooling water passage of the fuel cell 1 in order to cool the fuel cell 1 in operation. A system 5 is provided. The water circulation system 5 conveys water to the circulation passages 5a and 5b, the heat exchanger 6 provided adjacent to the off-gas combustor 38, through which the exhaust gas from the off-gas combustor 38 passes and is heated by the heat of the exhaust gas. And a water conveyance source 51 such as a pump.

  As shown in FIG. 1, the oxidant gas passage 2 includes an oxidant gas transport source 20 formed of a blower or the like, and a forward path 2 a from the oxidant passage inlet 1 e of the fuel cell 1, and an oxidant passage of the fuel cell 1. And a return path 2b from the outlet 1f to the exhaust section 28.

  Now, when the operation of the fuel cell 1 is started, it is necessary to start up the operation of the reformer 40. Therefore, the reformer 40 is heated to a high temperature by burning the combustible gas supplied from the blower 45 in the reformer combustor 43, and in this state, the reforming raw material (for example, natural gas, city gas, etc.) and the raw material are heated. Water is supplied to the reformer 40 through the passages 41 and 42. Then, a reforming reaction using the steam generated from the raw material occurs in the reformer 40, the reforming raw material is reformed as a fuel gas, and from the outlet 4 a of the reformer 40 toward the forward path 3 a of the fuel gas passage 3. Supplied.

  However, at the beginning of the reformer 40, the composition of the reformed gas reformed by the reformer 40 is not necessarily stable. Therefore, at the beginning of the reformer 40, the inlet valve 30 and the outlet valve 33 are closed, and the fuel gas is not supplied to the fuel cell 1. The first off-gas valve 34 is closed. At the beginning of the operation of the reformer 40, the bypass valve 36 and the second offgas valve 37 are open. Therefore, at the beginning of the operation of the reformer 40, the fuel gas is supplied to the offgas combustor 38 via the forward path 3 a, the bypass valve 36, the bypass passage 35, and the second offgas valve 37, and burns in the offgas combustor 38. . Thus, the off-gas combustor 38 is combusted and heated, and the exhaust gas of the off-gas combustor 38 passes through the heat exchanger 6 to heat the heat exchanger 6 and reach the exhaust section 28.

  Here, when the water in the water circulation system 5 passes through the heat exchanger 6 by the operation of the water conveyance source 51, the water is heat-exchanged and heated. Thus, since the water heated by the heat exchanger 6 flows through the cooling water passage of the fuel cell 1 through the circulation passage 5b, the fuel cell 1 is preheated at the start of operation of the reformer 40. Thus, if the fuel cell 1 is preheated when the operation of the fuel cell 1 is started, the fuel cell 1 is dried from the inside thereof. Therefore, when the power generation is started, the flooding phenomenon inside the fuel cell 1 is caused. Can contribute to control. The heat exchanger 6 can function as a drying force assisting means for drying the inside of the fuel cell 1. The heat exchanger 6 and the water circulation system 5 function as fuel cell preheating means for preheating the fuel cell 1 from the inside and adjusting the moisture inside the fuel cell 1 before the operation of the fuel cell 1 is started. it can.

  At the start of operation of the reformer 40, although it depends on the type of the reformer 40, it generally stabilizes in about 5 to 70 minutes. When the start-up of the operation of the reformer 40 is completed, the reforming reaction in the reformer 40 is stabilized, so that the bypass valve 36 and the second offgas valve 37 are closed, and the combustion in the offgas combustor 38 is stopped. At the same time, the inlet valve 30, the outlet valve 33, and the first off-gas valve 34 are opened, and the fuel gas is supplied from the outlet 4a of the reformer 40 to the fuel electrode of the fuel cell 1 through the forward path 3a and the inlet valve 30. Further, since the oxidant gas transport source 20 operates, the oxidant gas (generally air) is supplied from the forward path 2 a of the oxidant gas path 2 to the oxidant electrode of the fuel cell 1. As a result, a power generation reaction occurs in the fuel cell 1 and operation is performed.

  By the way, when the fuel cell 1 is in a steady operation, the second off-gas valve 37 is closed, combustion in the off-gas combustor 38 is stopped, and water in the water circulation system 5 is not heated in the heat exchanger 6. Therefore, if the water conveyance source 51 is driven to continue the water circulation, the fuel cell 1 can be cooled from the inside by the water circulating in the water circulation system 5.

  When the fuel cell 1 is in steady operation, the fuel off-gas after the power generation reaction discharged from the outlet 1b of the fuel electrode of the fuel cell 1 is the return path 3b, the opened outlet valve 33, and the opened first off-gas valve. 34 is supplied from the inlet 43 a to the reformer combustor 43 and burned by the reformer combustor 43. At this time, the blower 45 is also generally operated, and the combustible gas supplied by the blower 45 is combusted in the reformer combustor 43. However, the blower 45 is stopped when the reformer 40 can be heated to be suitable for the reforming reaction simply by burning the fuel off-gas in the reformer combustor 43.

  FIG. 2 shows a process when the operation of the fuel cell 1 is started. As shown in FIG. 2, when the start switch of the control device 7 is operated at time T1, when the time T3 is exceeded, the start-up operation of the reformer 40 becomes stable. From time T1 to time T4, combustion in the off-gas combustor 38 is continued and the heat exchanger 6 is heated, so that the temperature of the water in the water circulation system 5 flowing through the heat exchanger 6 gradually increases. As a result, during the start-up operation of the reformer 40, the fuel cell 1 is gradually preheated. Accordingly, the interior of the fuel cell 1 is dried by the water in the water circulation system 5 from time T1 to time T4. Note that, from time T1 to time T4, depending on the type of the reformer 40, etc., it is generally about 5 to 70 minutes.

  By the way, if the operation of the fuel cell 1 is continued, water is generated at the oxidant electrode of the fuel cell 1 by the power generation reaction. When the generated water is excessively accumulated in the fuel cell 1, as described above, a flooding phenomenon may occur in which the flow path of the gas passage in the fuel cell 1 is blocked with the generated water. In this case, there is a risk of affecting gas permeability in the fuel cell 1. Even if the operation of the fuel cell 1 is stopped, this water may remain in the fuel cell 1 until the next operation restart of the fuel cell 1. If water remains until the next operation restart of the fuel cell 1 in this way, when the operation of the fuel cell 1 is restarted, a flooding phenomenon is likely to occur, so that the gas passage of the fuel cell 1 is blocked with water, There is a possibility of affecting the power generation output of the fuel cell 1.

Therefore, according to the present embodiment, when the operation of the fuel cell 1 is finished, if there is a possibility that the flow path of the gas passage in the fuel cell 1 is clogged with water, the control device 7 constituting the moisture adjusting means 7 The oxidant gas transport source 20 such as a blower, a fan, and a compressor is turned on for a predetermined time (for example, 3 seconds to 120 minutes, 20 seconds to 60 minutes, 30 seconds to 10 minutes) according to the progress history during operation of the fuel cell 1. ) Drive. Thus, the control device 7 supplies an oxidant gas (generally air) to the oxidant electrode of the fuel cell 1 and executes a moisture adjustment process for ending that dries the oxidant electrode of the fuel cell 1. And can function as moisture adjustment means.

Further, according to this embodiment, when the operation of the fuel cell 1 that has been stopped is started, the flow path of the gas passage in the fuel cell 1 may be blocked with water. start internal state (moisture conditions in the previous in operation before the start of the internal elapsed history (for example, a fuel cell 1), the internal state (moisture state at the time of previous operation end of the fuel cell 1), the last fuel cell 1 The control device 7 constituting the moisture adjusting means drives the oxidant gas transport source 20 such as a blower, a fan, and a compressor in accordance with at least one of the conditions of the surrounding environment after the operation is stopped. As a result, an oxidant gas (generally air) is supplied to the oxidant electrode of the fuel cell 1 and a moisture adjustment process for starting is performed to dry the oxidant electrode of the fuel cell 1.

  As a result, when the operation of the fuel cell 1 is started, the moisture in the oxidant electrode of the fuel cell 1 is optimized from the beginning, and the flooding phenomenon is suppressed when the operation is shifted to the operation. For this reason, the operation of the fuel cell 1 can be performed satisfactorily.

  According to this embodiment, in the moisture adjustment process, the flow rate V1 per unit time of the oxidant gas is generally set smaller than the flow rate V2 per unit time during steady operation of the fuel cell 1. (V1 <V2). This is advantageous in reducing power consumption when supplying the oxidizing gas. However, the present invention is not limited to this, and in some cases, V1 = V2, V1≈V2, and V1> V2 can be set. Other embodiments can be similarly set such as V1 <V2.

According to the present embodiment, as described above, when the operation of the fuel cell 1 is started, the operation of the reformer 40 is started. However, the control device 7 constituting the moisture adjusting means The above-described start moisture adjustment processing is executed by overlapping in time during operation. That is, as shown in FIG. 2, the control device 7 overlaps in time with the start- up operation of the reformer 40 until the operation of the reformer 40 becomes stable, and the above-described start moisture Run the adjustment process in parallel. As a result, the time for moisture adjustment processing is saved without taking extra time, and it is possible to prevent the rise time of the fuel cell 1 from being prolonged.

Further, the moisture adjustment process for starting is performed by supplying an oxidant gas to the oxidant electrode of the fuel cell 1. For this reason, the oxidant gas conveyance source 20 such as a blower, a fan, and a compressor for supplying the oxidant gas is driven in the moisture adjustment process, and operation noise is often generated. On the other hand, even when the operation of the reformer 40 is started, the operation noise of the blower 45 and the like of the reforming system 4 is generated. Therefore, if the moisture adjustment process for start is executed in parallel with the time when the operation of the reformer 40 is started until the operation of the reformer 40 is stabilized, the reforming system is performed. Since the generation time of the operation sound at the rise of 4 and the generation time of the operation sound in the moisture adjustment process overlap in time, it is possible to prevent the generation time of the operation sound from being prolonged.

FIG. 3 shows a second embodiment. The second embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started, before the fuel cell 1 supplies power to the load, a history of progress before the start of the fuel cell 1 (for example, an internal state during operation of the fuel cell 1 (humidity state)) The internal state of the fuel cell 1 at the end of operation (humidity state) , the state of the surrounding environment after the fuel cell 1 is stopped, etc. A gas (generally air) is supplied to dry the oxidant electrode of the fuel cell 1.

In the following, different parts will be mainly described. Parts having common functions are denoted by common reference numerals. According to the present embodiment, similar to the first embodiment, when the operation of the fuel cell 1 is finished and when the operation is started, the history of the start of the fuel cell 1 before starting (for example, the fuel cell 1) Depending on the internal state during operation (humidity state) , the internal state at the end of operation of the fuel cell 1 (humidity state) , the state of the surrounding environment after the operation of the fuel cell 1 (humidity), etc.) The control device 7 constituting the moisture adjusting means drives the oxidant gas transport source 20 such as a blower, a fan, and a compressor, supplies the oxidant gas to the oxidant electrode of the fuel cell 1 and dries the oxidant electrode. Execute the moisture adjustment process for end or start . As a result, when the operation of the fuel cell 1 is started, moisture in the oxidant electrode of the fuel cell 1 is optimized from the beginning. For this reason, when the operation is started, the flooding phenomenon is suppressed, and the fuel cell 1 can be operated satisfactorily.

  According to the present embodiment, as shown in FIG. 3, the heat exchanger 6 is formed of a first heat exchanger 61 and a second heat exchanger 62. At the start of operation of the reformer 40, the bypass valve 36 and the second offgas valve 37 are opened while the inlet valve 30, the outlet valve 33, and the first offgas valve 34 are closed. The fuel gas discharged from the outlet 4a is supplied to the off-gas combustor 38 through the forward path 3a, the bypass valve 36 and the second off-gas valve 37, and combusted in the off-gas combustor 38 together with the air supplied from the air blower 39. The exhaust gas thus burned passes through the first heat exchanger 61 and the second heat exchanger 62 and reaches the exhaust part 28, so that the first heat exchanger 61 and the second heat exchanger 62 are heated.

  Then, at the start of the operation of the reformer 40, as can be understood from FIG. 3, the water in the water circulation system 5 passes through the second heat exchanger 62 by the operation of the water conveyance source 51. Heat is exchanged in the exchanger 62 and heated. Since the heated water flows through the cooling water passage of the fuel cell 1, the fuel cell 1 is preheated from the inside when the reformer 40 starts up. Thus, when the fuel cell 1 is preheated when the operation of the fuel cell 1 is started, the drying of the fuel cell 1 proceeds from the inside (particularly from the oxidant passage of the fuel cell 1). The moisture inside is optimized. Therefore, when the operation is started, the flooding phenomenon is effectively suppressed.

  Furthermore, according to the present embodiment, at the start of operation of the reformer 40, as can be understood from FIG. 3, the oxidant gas transported by the oxidant gas transport source 20 is transferred to the first heat exchanger via the forward path 2a. 61, is preheated by the first heat exchanger 61, and is supplied to the inlet 1e of the oxidant passage of the fuel cell 1 in such a preheated state.

As described above, at the start of the operation of the reformer 40, the moisture adjustment process for starting supplying the warm oxidant gas preheated by the first heat exchanger 61 to the inside of the fuel cell 1 is performed. The cell 1 is further dried with oxidant gas from its inside (especially from the oxidant passage of the fuel cell 1). As a result, the moisture inside the fuel cell 1 is optimized, and the flooding phenomenon is further suppressed when the operation is started. The first heat exchanger 61 can function as a gas drying power increasing unit that increases the drying power of the gas that adjusts the moisture inside the fuel cell 1.

Also in this embodiment, when the operation is started, the control device 7 constituting the moisture adjustment means performs the above-described start moisture adjustment process by overlapping in time during the start-up operation of the reformer 40. Therefore, the time of moisture adjustment processing is saved without taking extra time, and it is possible to prevent the rise time of the fuel cell 1 from being prolonged.

FIG. 4 shows a third embodiment. The third embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started, before the fuel cell 1 supplies power to the load, the history of the fuel cell 1 before starting to start (for example, the internal state during the operation of the fuel cell 1, the fuel cell 1 The oxidant gas (generally air) is supplied to the interior of the fuel cell 1, particularly to the oxidant electrode, depending on the internal state at the end of the operation and the surrounding environment after the operation of the fuel cell 1 is stopped. Then, the oxidant electrode of the fuel cell 1 is dried. In the following, different parts will be mainly described. Parts having common functions are denoted by common reference numerals. Also in the present embodiment, when the operation of the reformer 40 is started, the control device 7 constituting the moisture adjustment means drives the oxidant gas transport source 20 so as to overlap with this in time, and the oxidant A moisture adjustment process for starting is performed by supplying gas to the oxidant electrode of the fuel cell 1 and drying the oxidant electrode. As a result, when the operation of the fuel cell 1 is started, the moisture of the oxidant electrode of the fuel cell 1 is made appropriate. Therefore, the flooding phenomenon is suppressed when the operation is started, and the operation of the fuel cell 1 can be performed satisfactorily. Note that the above-described moisture adjustment process (end moisture adjustment process) can also be performed when the operation of the fuel cell 1 is terminated.

  According to the present embodiment, as shown in FIG. 4, a warming-up device 9 that is heated to a high temperature by electricity, chemical reaction, or warm water is provided. Further, in order to cool the fuel cell 1 in operation, a water circulation system 5 in which water circulates through the cooling water passage of the fuel cell 1 is provided. The water circulation system 5 includes circulation passages 5a and 5b, a warm-up device 9, and a water conveyance source 51 such as a pump for conveying water.

  At the start of operation of the reformer 40, the warm-up device 9 is heated by the moisture adjustment process. Therefore, when the water conveyance source 51 is driven, the water in the water circulation system 5 passes through the warm-up device 9 and is heated by the warm-up device 9, circulates in the water circulation system 5 as hot water, and thus the fuel cell 1 is preheated. As described above, when the fuel cell 1 is preheated when the operation of the fuel cell 1 is started (that is, at the start of the operation of the reformer 40), the inside of the fuel cell 1 is dried and moisture is made appropriate. The Therefore, the flooding phenomenon is further suppressed when the operation is started.

Also in this embodiment, the starting moisture adjustment process is executed so as to overlap in time when the reformer 40 starts up. At this time, the oxidant gas is preheated through the warm-up device 9. . And since the preheated oxidant gas is supplied into the fuel cell 1, the drying power by the oxidant gas can be increased. Therefore, it is advantageous to finish the moisture adjustment process of the oxidant gas in the fuel cell 1 in a short time. The warming-up device 9 can function as a drying force assisting unit that assists in drying the inside of the fuel cell 1.

The fourth embodiment shown in FIG. 5 has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started, before the fuel cell 1 supplies power to the load, a history of progress before the start of the fuel cell 1 (for example, an internal state during operation of the fuel cell 1 (humidity state)) The internal state of the fuel cell 1 at the end of operation (humidity state) , the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped, etc.) An oxidant gas (generally air) is supplied to the fuel cell 1 to dry the oxidant electrode. Hereinafter, a description will be given centering on differences from the first embodiment. Parts having common functions are denoted by common reference numerals. According to the present embodiment, as shown in FIG. 5, a warming-up device 9 is provided that is heated to a high temperature by electricity, chemical reaction, or warm water. In order to cool the fuel cell 1 in operation, a water circulation system 5 is provided in which water circulates through a cooling water passage of the fuel cell 1. The water circulation system 5 includes circulation passages 5a and 5b, a heat exchanger 6 provided adjacent to the warm-up device 9, and a water conveyance source 51 such as a pump for conveying water.

Also in this embodiment, the starting moisture adjustment process is executed in a time-overlapping manner at the start of operation of the reformer 40. Since the warm-up device 9 is heated at the start of the operation of the reformer 40, as can be understood from FIG. 5, the oxidant gas supplied to the oxidant electrode of the fuel cell 1 by the oxidant gas transport source 20 is Heated by the warm-up device 9, further heats the heat exchanger 6 and is supplied to the inlet 1 e of the oxidant electrode of the fuel cell 1. As a result, the fuel cell 1 is dried from the inside. The warm-up device 9 can function as gas drying power increasing means for increasing the drying power of the gas that adjusts the moisture inside the fuel cell 1.

  Furthermore, since the water conveyance source 51 is driven in the moisture adjustment process described above, the water in the water circulation system 5 passes through the heat exchanger 6 and is heated by the heat exchanger 6 as can be understood from FIG. Since the heated water is supplied to the fuel cell 1 in this way, the fuel cell 1 can be preheated at the start of operation of the reformer 40, thereby increasing the dryness of the fuel cell 1, The flooding phenomenon of the fuel cell 1 is further suppressed. The heat exchanger 6 can function as a drying force assisting means for drying the inside of the fuel cell 1 at the start of operation of the reformer 40.

FIG. 6 shows a fifth embodiment. The fifth embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started, before the fuel cell 1 supplies power to the load, a history of progress before the start of the fuel cell 1 (for example, an internal state during operation of the fuel cell 1 (humidity state)) The oxidant gas at the oxidant electrode of the fuel cell 1 according to the internal state (humidity state) at the end of the operation of the fuel cell 1 and the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped) (Generally air) is supplied to dry the oxidant electrode of the fuel cell 1. Hereinafter, a description will be given centering on differences from the first embodiment. Parts having common functions are denoted by common reference numerals. According to the present embodiment, as shown in FIG. 6, the heat exchanger 6 heated by the exhaust gas from the reformer combustor 43 is provided. The water circulation system 5 includes circulation passages 5a and 5b, a heat exchanger 6, and a water conveyance source 51 such as a pump for conveying water.

  At the start of operation of the fuel cell 1 (that is, at the start of operation of the reformer 40), the heat exchanger 6 is heated with exhaust gas having heat discharged from the reformer combustor 43. For this reason, when the water conveyance source 51 is driven, the water in the water circulation system 5 passes through the heat exchanger 6 and is heated by the heat exchanger 6. Thus, since the water heated by the heat exchanger 6 is supplied to the fuel cell 1 at the start of operation of the fuel cell 1, the fuel cell 1 can be preheated at the start of operation of the reforming system 4. it can. The heat exchanger 6 can function as a drying force assisting means for drying the inside of the fuel cell 1 at the start of operation of the reforming system 4.

Furthermore, the moisture adjustment process for starting is performed in a time-overlapping manner at the start of the operation of the reforming system 4. That is, at the start of the operation of the reforming system 4, the oxidant gas transport source 20 operates to supply the oxidant gas to the oxidant electrode of the fuel cell 1. Therefore, the fuel cell 1 is dried from the inside. Thereby, the dryness of the fuel cell 1 can be increased. Therefore, when the operation is started, the flooding phenomenon of the fuel cell 1 is further suppressed.

FIG. 7 shows a sixth embodiment. The sixth embodiment has basically the same configuration and function as the fifth embodiment. Therefore, when the operation of the fuel cell 1 is started , before the load feeding of the fuel cell 1, a history of progress before the start of the fuel cell 1 (for example, an internal state (humidity state) during operation of the fuel cell 1 ) , Depending on the internal state (humidity state) at the end of the operation of the fuel cell 1 and the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped, an oxidant gas ( In general, air) is supplied to dry the inside of the fuel cell 1, particularly the oxidizer electrode. Hereinafter, a description will be given centering on differences from the first embodiment. Parts having common functions are denoted by common reference numerals. According to the present embodiment, as shown in FIG. 7, the heat exchanger 6 that is heated by the heat of the exhaust gas discharged from the reformer combustor 43 is provided. The heat exchanger 6 is formed by a first heat exchanger 61 and a second heat exchanger 62. The moisture adjustment process is performed in a time-overlapping manner when the reformer 40 starts operation. That is, the oxidant gas transport source 20 is activated at the start of the operation of the reformer 40, and the oxidant gas reaches the first heat exchanger 61 via the forward path 2a and is preheated by heat exchange in the first heat exchanger 61. And supplied to the inlet 1 e of the oxidant passage of the fuel cell 1.

  The water circulation system 5 includes circulation passages 5a and 5b, a second heat exchanger 62, and a water conveyance source 51 such as a pump for conveying water. When the combustible gas supplied by the blower 45 is combusted in the reformer combustor 43 and the reformer 40 is heated, the exhaust gas from the reformer combustor 43 is converted into the first heat exchanger 61 and the second heat. The exhaust 62 is reached through the exchanger 62. At this time, the exhaust gas heats the first heat exchanger 61 and the second heat exchanger 62.

  At the start of operation of the reformer 40, the water in the water circulation system 5 passes through the second heat exchanger 62 by the operation of the water conveyance source 51, and the water is heat-exchanged and heated in the second heat exchanger 62. . Since the heated water flows through the cooling water passage of the fuel cell 1 after passing through the circulation passage 5b, the fuel cell 1 is preheated from the inside during the start-up operation of the reformer 40. Therefore, the second heat exchanger 62 can function as a drying force assisting unit that assists in drying the inside of the fuel cell 1 during the start-up operation of the reformer 40.

  In the moisture adjustment process described above, when the oxidant gas transport source 20 is activated, the oxidant gas reaches the first heat exchanger 61 and is heated by heat exchange in the first heat exchanger 61, and the heated oxidation is performed. The agent gas is supplied to the inlet 1 e of the oxidant passage of the fuel cell 1.

As described above, when the moisture adjustment process is performed at the start of the operation of the reformer 40, the drying of the oxidant electrode of the fuel cell 1 proceeds, and therefore the flooding phenomenon inside the fuel cell 1 starts from the beginning of the operation. It is suppressed. Thus, the first heat exchanger 61 can function as a gas drying power increasing means for increasing the dry strength of the gas adjusting the moisture inside the fuel cell 1.

FIG. 8 shows a seventh embodiment. The seventh embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started , before the load feeding of the fuel cell 1, a history of progress before the start of the fuel cell 1 (for example, an internal state (humidity state) during operation of the fuel cell 1 ) , Depending on the internal state (humidity state) at the end of the operation of the fuel cell 1 and the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped, an oxidant gas ( In general, air) is supplied to dry the oxidant electrode of the fuel cell 1. Hereinafter, a description will be given centering on differences from the first embodiment. Parts having common functions are denoted by common reference numerals. According to the present embodiment, as shown in FIG. 8, when the operation of the fuel cell 1 is finished, a purge gas having a low activity (such as an inert gas such as nitrogen gas) is used to protect the interior of the reformer 40. A purge processing unit 8 is provided for supplying the reformer 40 to the reformer 40. As shown in FIG. 8, the purge processing unit 8 includes a passage 80 that supplies purge gas to the reformer 40, a purge gas source 81 that is connected to the passage 80, and an on-off valve 82 that opens and closes the passage 80.

  Further, when the operation of the fuel cell 1 is terminated, in order to protect the interior of the reformer 40, a purge gas (inert gas such as nitrogen gas) having a low activity is applied to the fuel cell 1 as shown in FIG. A purge processing unit 8X for supplying is provided. As shown in FIG. 8, the purge processing unit 8X includes a passage 80X for supplying purge gas to the fuel cell 1, a purge gas source 81X connected to the passage 80X, and an on-off valve 82X for opening and closing the passage 80X.

  When the operation of the fuel cell 1 is terminated, the purge gas processing unit 8 supplies the purge gas into the reformer 40, and the combustible reformed gas remaining in the reformer 40 is supplied from the reformer 40. A purge process in which a purge gas having a low activity is sealed in the reformer 40 is performed. Further, purge gas is supplied into the fuel cell 1 by the purge gas processing unit 8X, the combustible fuel gas remaining in the fuel cell 1 is discharged from the fuel cell 1, and a purge gas having low activity is put into the fuel cell 1. The purge process is performed.

When the operation of the fuel cell 1 is ended, the control device 7 constituting the moisture adjusting means executes the ending moisture adjusting process in parallel with the above purge process in time. That is, since the oxidant gas is supplied to the oxidant electrode of the fuel cell 1 in the moisture adjustment process, the oxidant gas transport source 20 is driven in the moisture adjustment process, so that an operation noise is often generated. On the other hand, even when supplying Therefore purge gas to the purge unit 8 as described above in the reformer 4 0, operation sound is generated. Therefore, when the operation of the fuel cell 1 is ended, the generation time of the operation noise in the purge process and the generation time of the operation sound in the moisture adjustment process for the end can be overlapped in time, and the generation time of the operation sound Can be prolonged.

FIG. 9 shows a main part of the eighth embodiment. The eighth embodiment has basically the same configuration and effect as the first embodiment. Therefore, when the operation of the fuel cell 1 is started , before the load feeding of the fuel cell 1, a history of progress before the start of the fuel cell 1 (for example, an internal state (humidity state) during operation of the fuel cell 1 ) , Depending on the internal state (humidity state) at the end of the operation of the fuel cell 1 and the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped, an oxidant gas ( In general, air) is supplied to dry the inside of the fuel cell 1, particularly the oxidizer electrode. In the following, different parts will be mainly described. Parts having common functions are denoted by common reference numerals. According to the present embodiment, as shown in FIG. 9, the wet state detecting means for detecting the wet state of the oxidant electrode of the fuel cell 1 is provided. The wet state detection means is a distance detection sensor method for detecting the thickness or distance in the stacking direction of the stack 13 of the fuel cell 1, or a load detection sensor method for detecting a load in the stacking direction of the stack 13 of the fuel cell 1, or A humidity sensor system that detects the humidity of the oxidant off-gas after the power generation reaction discharged from the outlet of the oxidant electrode of the fuel cell 1 can be employed. When the moisture inside the fuel cell 1 is high, the stack 13 expands in the stacking direction. Therefore, if the load, thickness, distance, etc. in the stacking direction are detected, the wet state inside the fuel cell 1 is indirectly detected. Detected.

  That is, when the inside of the fuel cell 1 is excessively wet, the thickness or distance in the stacking direction of the stack 13 of the fuel cell 1 increases, or the load in the stacking direction of the stack 13 of the fuel cell 1 increases. . On the other hand, when the oxidant electrode of the fuel cell 1 is in an excessively dry state, the thickness or distance in the stacking direction of the stack 13 of the fuel cell 1 is reduced, or the load in the stacking direction of the stack 13 of the fuel cell 1 is reduced. Or decrease. Further, if the humidity of the oxidant off-gas after the power generation reaction discharged from the outlet 1f of the oxidant electrode of the fuel cell 1 is considerably high, it can be determined that the inside of the fuel cell 1 is excessively wet, and the oxidant off-gas is concerned. If the humidity of the fuel cell is quite low, it can be determined that the inside of the fuel cell 1 is excessively dry.

Based on the detection signal of the wet state detection unit, the control device 7 constituting the wet state determination unit is in operation of the fuel cell 1, at the end of the operation of the fuel cell 1, or during the stop of the operation of the fuel cell 1. Alternatively, at the start of operation of the fuel cell 1, it can be determined whether or not the oxidant electrode inside the fuel cell 1 is in a wet state or a dry state.

FIG. 10 shows a ninth embodiment. The ninth embodiment has basically the same configuration and function as the first embodiment. Therefore, when starting the operation of the fuel cell 1, before the load feeding of the fuel cell 1, the history of the fuel cell 1 before starting to start (for example, the internal state during the operation of the fuel cell 1, the operation of the fuel cell 1) The oxidant gas (generally air) is supplied to the oxidant electrode of the fuel cell 1 according to the internal state at the time of termination, the state of the surrounding environment after the operation of the fuel cell 1 is stopped, etc. Dry the inside. In the following, different parts will be mainly described. FIG. 10 shows an example of a flowchart executed by the control device 7. The flowchart is not limited to this. As shown in FIG. 10, it is determined whether the start switch is activated and the fuel cell power generation system is being activated (step S102). If it is activated, when the operation of the fuel cell 1 is ended last time, it is determined whether or not the moisture inside the fuel cell 1 is normal at the end of the previous operation (step S104). If the moisture of the fuel cell 1 is normal when the operation of the fuel cell 1 is completed last time, an oxidant gas (flow rate per unit time: const) flows through the inside of the fuel cell 1, particularly the oxidant electrode ( Step S106).

  Further, when the operation of the fuel cell 1 is finished last time, it is determined whether or not the moisture of the fuel cell 1 is dry (whether it is wet) (step S108). When the inside of the fuel cell 1 is dry at the end of the previous operation, the flow rate of the oxidant gas (cathode air) is reduced by k2 (flow rate per unit time: const-k2), and the oxidant gas. Is supplied to the inside of the fuel cell 1, particularly to the oxidant electrode (step S110).

Also, at the end of the previous operation of the fuel cell 1, if the inside of the fuel cell 1 is wet, the flow rate of the oxidant gas (cathode air) is increased by an amount equivalent to k1 (flow rate per unit time: const + k1) The oxidant gas is supplied to the inside of the fuel cell 1, particularly to the oxidant electrode (step S112). And it may or determined to exit the moisture adjustment process for starting (step S114), and ends the moisture adjustment process for starting well that ends. Whether or not to end can be determined based on an internal timer. When it is necessary to continue the moisture adjustment process for the start, the process returns to step S104. Thus, the drying power (gas flow rate) of the drying gas supplied to the inside of the fuel cell 1 is adjusted according to the wet state of the fuel cell 1 at the end of the previous operation.

  Instead of adjusting the flow rate of the oxidant gas, the temperature of the oxidant gas may be adjusted. That is, when the moisture of the fuel cell 1 is wet at the end of the previous operation, the temperature of the oxidant gas is increased. When the moisture of the fuel cell 1 is dry at the end of the previous operation, the temperature of the oxidant gas is set low.

As described above, according to the present embodiment, as understood from the flowchart shown in FIG. 10, when the operation of the fuel cell 1 was finished last time, whether the moisture inside the fuel cell 1 is normal or whether the fuel cell 1 is normal. It is determined whether the moisture inside the fuel cell is dry or the moisture of the fuel cell 1 is wet, and an oxidant gas having a flow rate and / or temperature corresponding to the determination is supplied to the oxidant electrode of the fuel cell 1. (Moisture adjustment processing for starting ) can be made appropriate, and the moisture state of the fuel cell 1 can be made appropriate.

FIG. 11 shows a tenth embodiment. The tenth embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started , before the load feeding of the fuel cell 1, a history of progress before the start of the fuel cell 1 (for example, an internal state (humidity state) during operation of the fuel cell 1 ) , Depending on the internal state (humidity state) at the end of the operation of the fuel cell 1 and the surrounding environment state (humidity) after the operation of the fuel cell 1 is stopped, an oxidant gas ( In general, air) is supplied to dry the oxidant electrode of the fuel cell 1. In the following, different parts will be mainly described. Parts having common functions are denoted by common reference numerals.

  FIG. 11 shows a flowchart executed by the control device 7. Based on the humidity sensor or the like, an average value of the atmospheric humidity from the end of the previous operation of the fuel cell 1 to the start of the current operation is obtained (step S202). That is, the average humidity of the surrounding environment of the fuel cell 1 when the operation of the fuel cell 1 is stopped is obtained. The average humidity can be an average value of humidity every predetermined time. And the magnitude | size of the humidity of the surrounding environment in which the fuel cell 1 is installed is determined (step S204, 206). When it is determined that the humidity of the surrounding environment in which the fuel cell 1 is installed is relatively high, the control device 7 that forms the moisture adjusting means oxidizes per unit time supplied to the oxidant electrode of the fuel cell 1. The coefficient α1 (α1> 1) is selected so as to increase the flow rate of the oxidant gas, the basic flow rate of the oxidant gas per unit time supplied to the oxidant electrode of the fuel cell 1 is const × the coefficient α1, and the oxidant The drying power by gas is relatively increased (steps S208 and S210). Steps S208 and S210 have gas drying power increasing means for relatively increasing the drying power of the gas that is supplied to the oxidant electrode of the fuel cell 1 and adjusts the moisture of the oxidant electrode.

  Further, when it is determined that the humidity of the surrounding environment where the fuel cell 1 is installed is relatively low, the coefficient α3 (α3) is set so that the flow rate of the oxidant gas supplied to the oxidant electrode of the fuel cell 1 is decreased. <1) is selected, the basic flow rate per unit time supplied to the oxidant electrode of the fuel cell 1 is set to const × coefficient α3, and the drying power by the oxidant gas is relatively reduced (steps S212 and 214). Steps S212 and S214 include gas drying power reducing means (gas drying power adjusting means) that relatively decreases the drying power of the gas that is supplied to the oxidant electrode of the fuel cell 1 to adjust the moisture of the oxidant electrode. .

  When it is determined that the humidity of the surrounding environment where the fuel cell 1 is installed is relatively intermediate, the coefficient α2 (α2) is set so that the flow rate of the oxidant gas supplied to the oxidant electrode of the fuel cell 1 is intermediate. 1) is selected, the basic flow rate per unit time supplied to the oxidant electrode of the fuel cell 1 is set to const × coefficient α2, and the drying power by the oxidant gas is adjusted (steps S216 and S218). Steps S216 and S218 have gas drying force intermediate setting means for setting the drying force of the gas that is supplied to the oxidant electrode of the fuel cell 1 to adjust the moisture of the oxidant electrode to an intermediate region. Thereby, according to the humidity of the atmosphere which is the ambient environment from the end of the previous operation to the start of the current operation, that is, according to the humidity of the ambient environment when the operation of the fuel cell 1 is stopped, Adjust the drying power of the supplied oxidant gas. Note that the temperature may be adjusted instead of the flow rate of the oxidant gas. In this case, an increase in the flow rate of the oxidant gas corresponds to an increase in the temperature of the oxidant gas. A decrease in the flow rate of the oxidant gas corresponds to a decrease in the temperature of the oxidant gas.

12 and 13 show Example 11. FIG. The eleventh embodiment has basically the same configuration and function as the first embodiment. Therefore, when the operation of the fuel cell 1 is started, before power is supplied from the fuel cell 1 to the load, a history of progress before starting the fuel cell 1 (for example, an internal state during operation of the fuel cell 1 (humidity state) ) , The internal state at the end of operation of the fuel cell 1 (moisture state) , the state of the surrounding environment after the operation of the fuel cell 1 is stopped (humidity), etc.) A gas (generally air) is supplied to dry the oxidant electrode of the fuel cell 1. In the following, different parts will be mainly described. Parts having common functions are denoted by common reference numerals. According to the present embodiment, the control device 7 constitutes a wet state determination unit that determines the wet state of the oxidizer electrode of the fuel cell 1 at the end of the previous operation. The control device 7 that constitutes the moisture adjustment means performs the start moisture adjustment processing according to the above-described wet state determination means, with the time overlap during the start-up operation of the reformer 40.

Hereinafter, the wet state determination unit according to the present embodiment will be described. The wet state determination means determines the internal wet state of the fuel cell 1 at the end of the previous operation, and is a control obtained by statistically processing the cell voltage of the fuel cell 1 composed of a plurality of basic cells. Based on the index, the wet state inside the fuel cell 1 is determined. The control index is the skewness of the cell voltage distribution of the plurality of basic cells. In this case, it is possible to determine the state of moisture inside the fuel cell 1 based on the degree of distortion of the cell voltage distribution. That is, the moisture inside the fuel cell 1 can be detected effectively based on an abnormality that appears as a symmetric disturbance (asymmetrical) in the cell voltage distribution of the plurality of basic cells.

  For example, it is possible to estimate an abnormality of the cell due to excessive wetting (excess water) in the electrolyte of the cell, excessive drying of the electrolyte membrane (insufficient water), or the like. Further explanation will be added. FIG. 12 is a graph showing a distribution (cell voltage distribution) of the output voltage of each cell of the fuel cell 1. In FIG. 12, the horizontal axis represents the cell voltage, and the vertical axis represents the number of cell samples. In FIG. 12, the characteristic example in the standard state is indicated by a solid line M1, the characteristic example in an excessive water (flooding) state near the electrolyte membrane is indicated by a one-dot chain line M2, and the electrolyte membrane is excessively dried (dry out). An example of the characteristic is indicated by a dotted line M3.

  When the electrolyte membrane of the cell is in an excessively dry state or an excessive moisture state, as shown in FIG. 12, there is a tendency that the cell voltage varies and the base of the cell voltage distribution is widened. It can also be seen that the cell voltage distribution deviates from the normal distribution, and the symmetry of the distribution curve centered on the average value decreases. The reason is that if the gas passage is blocked by excess water, the cell voltage is greatly reduced, and a maximum value is generated at a position spaced downward from the average value of the cell voltage. .

  According to the present embodiment, the influence of the data separated from the average value is reflected relatively large in the value given by the statistical processing of the cell voltage distribution of the fuel cell 1. Further, the separation direction from the average value of the data separated from the average value is reflected in the value. For this purpose, the average value of the cell voltage distribution and the cube value (distortion) of the difference between the measured values are introduced into the statistical processing. It is possible to estimate an abnormal value due to flooding that occurs in a portion spaced below the average value of the cell voltage, a shift in the peak characteristics of the cell voltage distribution due to moisture adjustment of the electrolyte membrane, and the like by “the value”. An appropriate operation of the fuel cell 1 is performed by controlling the fuel cell power generation system based on such an estimation result.

  Further explanation will be added. The fuel cell 1 is a polymer electrolyte membrane type fuel cell, and is configured by stacking a plurality of unit cells. For example, tens to hundreds of unit cells are stacked. The output voltage of each cell is detected by a cell voltage monitor and sent to the control device 7.

FIG. 13 is a flowchart for explaining the statistical processing mode of the control device 7. According to this flowchart, the control device 7 reads output voltage (cell voltage) data of each unit cell of the fuel cell 1 (step S302). Based on the read cell voltage data, the cell voltage variance (or standard deviation) is calculated (step S304). When the difference between each data xi and the average xm is Δx, the variance V is an average value of the square of Δx (V = Σ _n Δxi ² / n). Here, n is the number of data, and Σ _n means that a cumulative value is obtained for ₁ to n pieces of data. The standard deviation σ is obtained as the square root of the variance V. The variance V (or standard deviation) is an index indicating whether the measurement results of the entire cell voltage are gathered at an average or scattered. The smaller the variance V, the closer the data is to the average value. The greater the variance V, the more scattered the data from the average value.

According to the flowchart described above, it is determined whether or not the calculated variance V is larger than a design threshold value (step S306). If not, it is determined that the cell voltage distribution is normal (step S308), and the state flag indicating the wet state inside the fuel cell 1 is set to “normal”. Thereafter, the process returns to the original process. When the variance V is larger than the design threshold value, the skewness s is calculated (step S310). The skewness s is calculated as s = (1 / n) Σ _n (xi−Xm) ³ / σ ³ .

  This skewness s is a measure that represents the degree of asymmetry around the average value of the cell voltage distribution to some extent. The skewness s can be either positive or negative.

  As an example of the distribution in which the skewness s is a “positive” value, the cell voltage distribution is a single peak type distribution, the peak is shifted to the left, and the tail on the right side of the distribution is elongated. If the moisture supplied to the electrolyte membrane 10 of the cell is insufficient and the ionic conductivity of the electrolyte membrane 10 is lowered to reduce the cell performance (dry out), such a distribution is likely to occur.

  As an example of the distribution in which the skewness s is a “negative” value, there is a shape in which the cell voltage distribution is a single peak type distribution, the peak is shifted to the right, and the left side of the distribution is elongated. When the flooding phenomenon occurs, such a distribution tendency tends to occur.

  As an example in which the degree of distortion s of the electrolyte membrane is close to “0”, there is a case where the cell voltage distribution is close to a symmetrical shape around the average.

  As described above, the signs of skewness “positive” and “negative” indicate the tendency of the distribution, and the magnitude of the skewness s is an index indicating the degree of the skewness of the normal distribution. However, if the cell voltage distribution is symmetric, the skewness will be “0”, but even non-symmetric distributions may be “0”. ing.

  According to the flowchart described above, it is determined whether or not the obtained skewness s is larger than the reference value cl (step S312). The reference value cl is set for each model of the fuel cell 1, and is set to −2 to 4, for example. If NO in step S312, the control device 7 determines that the electrolyte membrane 10 of the cell is in a dry state (dry out), and sets a state flag indicating the operating state of the fuel cell 1 to “dry out”. In order to retain moisture in the electrolyte membrane 10, the flow rate per unit time of the oxidant gas (cathode air) is decreased and the flow rate is decreased by k3 (step S316). Thereafter, the process returns to the original process.

  When the variance is large and the obtained skewness is smaller than the reference value cl (YES), the control device 7 determines that it is in the flooding state, and sets the state flag indicating the operation state of the fuel cell 1 to “flooding”. Setting is made (step S318).

  Further, in order to determine the degree of flooding, it is determined whether or not the skewness s is smaller than the reference value c2 (step S320). When the skewness s is negative and the value is smaller than the reference value c2, the flow rate per unit time of the oxidant gas (cathode air) supplied to the oxidant electrode of the fuel cell 1 is increased by kl. Thereby, excess moisture in the cell is removed (step S322). Thereafter, the process returns to the original process.

When the skewness s is negative and the value is larger than c2, the flow rate per unit time of the oxidant gas (cathode air) supplied to the oxidant electrode inside the fuel cell 1 is increased by k2 (k2> kl). . As a result, excess water in the cell is removed earlier (step S324). Thereafter, the process returns to the original process.

In this way, the internal moisture adjustment of the fuel cell 1 based on the statistical processing of the cell voltage is performed by periodically repeating steps S302 to S324. Instead of adjusting the flow rate of the oxidant gas supplied to the oxidant electrode inside the fuel cell 1 to adjust the cell voltage, the temperature of the oxidant gas may be adjusted instead.

(Other examples)
In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist.
[Additional Item 1] A fuel cell having an electrolyte membrane and a fuel electrode and an oxidant electrode sandwiching the electrolyte membrane, an oxidant gas passage for supplying an oxidant gas to the oxidant electrode of the fuel cell, and the fuel cell A fuel cell power generation system comprising a fuel gas passage for supplying fuel gas to the fuel electrode, wherein gas is supplied to the fuel cell before load feeding to adjust moisture inside the fuel cell. When the wet state determination unit determines that the wet state inside the fuel cell is relatively high, the moisture adjustment unit is configured to determine the wet state of the fuel cell. Adjusting at least one of the temperature, humidity and flow rate of the gas supplied to adjust the moisture to the battery to relatively increase the drying power of the gas, and the wet state inside the fuel cell is Relatively low And the wetness state determination means adjusts at least one of the temperature, humidity and flow rate of the gas supplied to adjust the moisture inside the fuel cell. A fuel cell power generation system characterized by relatively reducing the drying power of the gas.

  The present invention can be used in fuel cell power generation systems for vehicles, stationary devices, portable devices, electronic devices, electric devices, and the like.

1 is a configuration diagram of a fuel cell power generation system according to Embodiment 1. FIG. FIG. 3 is a process diagram when starting operation of the fuel cell power generation system according to Embodiment 1; 6 is a configuration diagram of a fuel cell power generation system according to Embodiment 2. FIG. 6 is a configuration diagram of a fuel cell power generation system according to Embodiment 3. FIG. 6 is a configuration diagram of a fuel cell power generation system according to Embodiment 4. FIG. FIG. 6 is a configuration diagram of a fuel cell power generation system according to a fifth embodiment. 10 is a configuration diagram of a fuel cell power generation system according to Embodiment 6. FIG. FIG. 10 is a configuration diagram of a fuel cell power generation system according to a seventh embodiment. FIG. 10 is a configuration diagram in the vicinity of a stack of a fuel cell having a wet state detection unit according to an eighth embodiment. 10 is a flowchart of a fuel cell power generation system according to Embodiment 9. 12 is a flowchart of a fuel cell power generation system according to Example 10. 12 is a graph showing a relationship between a cell voltage and the number of samples according to Example 11. 12 is a flowchart of a fuel cell power generation system according to Example 11.

Explanation of symbols

  In the figure, 1 is a fuel cell, 13 is a stack, 2 is an oxidant gas passage, 2a is an outgoing route, 2b is a return route, 3 is a fuel gas passage, 3a is an outgoing route, 3b is a return route, 4 is a reforming system, and 40 is a modified system. 43, reformer combustor, 45 blower, 5 water circulation system, 51 water transfer source, 6 heat exchanger, 61 first heat exchanger, 62 second heat exchanger, 7 A control device (moisture adjusting means), 8 is a purge processing unit, and 9 is a warm-up device.

Claims (8)

A fuel cell having an electrolyte membrane and a fuel electrode and an oxidant electrode sandwiching the electrolyte membrane, an oxidant gas passage for supplying an oxidant gas to the oxidant electrode of the fuel cell, and a fuel to the fuel electrode of the fuel cell A fuel gas power generation system including a fuel gas passage for supplying gas, and supplying moisture to the inside of the fuel cell before load power feeding to adjust moisture inside the fuel cell;
When starting the operation of the fuel cell,
At least one of the moisture state inside the fuel cell during the previous operation, the moisture state inside the fuel cell at the end of the previous operation, and the humidity state of the surrounding environment of the fuel cell after the previous operation stop According to the progress history before starting the fuel cell,
A fuel cell power generation system comprising moisture adjustment means for performing moisture adjustment processing for starting to dry the inside of the fuel cell with a gas supplied to the inside of the fuel cell.   2. The reformer according to claim 1, wherein a reformer that reforms the reforming raw material to generate a fuel gas is provided, and when the operation of the fuel cell is started, the moisture adjusting means starts up the reformer. A fuel cell power generation system, wherein the moisture adjustment process for start is executed in time overlap with the operation. In Claim 2, when the operation of the fuel cell is terminated, a purge processing unit is provided for supplying a purge gas formed of an inert gas to the reformer,
When starting the operation of the fuel cell, the moisture adjustment means executes the moisture adjustment process for starting,
To end the operation of the fuel cell, the humidity adjustment unit, wherein the gas supplied to the fuel cell the purge gas temporally overlap the purge process for supplying to the reformer by the purge gas processing unit A fuel cell power generation system that performs a moisture adjustment process for ending to dry the inside of the fuel cell.   4. The temperature of the gas according to claim 1, wherein the moisture adjustment unit performs the moisture adjustment process for starting to adjust moisture inside the fuel cell. 5. A fuel cell power generation system comprising gas drying power increasing means for adjusting at least one of humidity and flow rate to increase the drying power of the gas. The information on the atmospheric humidity at the end of the previous operation, the information on the atmospheric humidity at the start of the current operation, and the end of the previous operation in any one of claims 1 to 4. Ambient environment humidity determination means for determining the humidity of the ambient environment of the fuel cell based on at least one of the information on the humidity of the atmosphere until the start of operation this time,
When the ambient environment humidity determination means determines that the humidity of the surrounding environment is relatively high, the moisture adjustment means includes at least one of the temperature, humidity, and flow rate of the gas supplied to the fuel cell. To relatively increase the drying power by the gas, and
When the ambient environment humidity determining means determines that the humidity of the surrounding environment is relatively low, the moisture adjusting means is at least one of the temperature, humidity, and flow rate of the gas supplied to the fuel cell. The fuel cell power generation system is characterized in that the drying power by the gas is relatively reduced by adjusting.   6. The fuel cell according to claim 1, wherein at least one of the operation of the fuel cell, the end of the operation of the fuel cell, the stop of the operation of the fuel cell, and the start of operation of the fuel cell is performed. The fuel cell power generation system according to claim 1, further comprising wet state determination means for determining a wet state inside the fuel cell.   7. The fuel cell according to claim 1, further comprising gas preheating means for preheating the gas supplied for moisture adjustment inside the fuel cell. system.   3. The operation of the fuel cell according to claim 1, wherein when the operation of the fuel cell is terminated, the moisture adjustment means performs a moisture adjustment process for ending the interior of the fuel cell with a gas supplied to the fuel cell. A fuel cell power generation system.

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