JPH0831439A - Fuel cell power generation plant - Google Patents

Abstract

PURPOSE:To keep fuel/oxidizer utilization factor of a fuel cell main body, and a battery voltage within a proper range even in the case where characteristic unbalance is generated between the fuel cell main bodies. CONSTITUTION:Fuel cell main bodies 1 each comprising a fuel pole and an oxidizer pole are electrically connected to each other in the number of (n) (n>=1) serially to form a string 2, and such strings 2 are electrically connected in parallel in the number of (m) (m>=2). To each string 2, a string current detector 31 is connected separately. A fuel supply damper 32 and an oxidizer supply damper 33 are provided on each fuel supply header 19 and an oxidizer supply header 20 of each string 2 respectively. Each fuel supply damper 32 and each oxidizer supply damper 33 adjust ratio of fuel flow and oxidizer flow to be supplied to each string 2 based on each string current detection value obtained by each string current detector 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power plant having a plurality of fuel cell bodies electrically connected in series or in parallel, and more particularly to improvement of a fuel / oxidant supply system.

[0002]

2. Description of the Related Art Generally, in a fuel cell power plant,
Since the output of the fuel cell main body of the stand is limited, it is necessary to incorporate a plurality of fuel cell main bodies when increasing the power generation output. However, since the battery operating voltage becomes too high and the rated voltage of the orthogonal transformation device becomes high only by the series connection, it is common to combine the series connection and the parallel connection.

Further, in such a fuel cell power generation plant, the fuel / oxidizer is supplied to a plurality of fuel cells so that the supply amount of the fuel / oxidizer to each fuel cell can be adjusted according to the output of the entire plant. The flow rate adjusting means for doing so is common to all fuel cell main bodies. Further, the recycle flow rate adjustment of the oxidant for suppressing the operating voltage of the fuel cell is performed by using the average value of all the cell voltages as a value representing the individual cell voltage.

FIG. 4 is a block diagram showing an example of a conventional fuel cell power plant. As shown in FIG. 4, n fuel cell main bodies 1 are electrically connected in series to form one string (series-connected cell group) 2. The m columns of strings 2 configured in this manner are electrically connected in parallel, and are electrically connected in parallel with an electrical system 3 including an orthogonal transformation device, and a load current is extracted from the electrical system 3. Has become. The electric system 3 is electrically connected in series with a total current detector 4 that measures a load current from the electric system 3. Further, a voltage detector 5 that detects the voltage of the fuel cell body 1 is individually connected to each fuel cell body 1.

Reference numerals 11 and 12 in the figure are for treating fuels such as hydrogen and oxidants such as air, and supplying them to the anode (fuel electrode) and cathode (oxidant electrode) of each fuel cell body 1. Fuel treatment system and oxidant treatment system. A fuel supply common pipe 13 and an oxidant supply common pipe 14 are connected to the fuel processing system 11 and the oxidant processing system 12, respectively. Then, in the fuel supply common pipe 13 and the oxidant supply common pipe 14, as a means for adjusting the supply flow rates of the fuel and the oxidant from these systems, a fuel flow control valve 15, a fuel flow meter 16, and an oxidizer. A flow control valve 17 and an oxidant flow meter 18 are provided respectively.

On the other hand, a fuel supply header 19 and an oxidant supply header 20 are individually provided at one end of each string 2, and are connected to the fuel supply common pipe 13 and the oxidant supply common pipe 14, respectively. Further, a fuel discharge header 21 and an oxidant discharge header 22 are individually provided at the other end of each string 2, and each fuel discharge header 2
1 is connected to the fuel discharge common pipe 23, and each oxidant discharge header 22 is connected to the oxidant discharge common pipe 24.
Further, a recycle pipe 25 for recycling a part of the discharged oxidant is connected to one end of the oxidant discharge common pipe 24, and the other end of the recycle pipe 25 is connected to the oxidant supply common pipe 14. There is. The recycle pipe 25 is provided with the oxidant supply common pipe 14 for discharging the oxidant discharged inside.
A recycle blower 26 for recycle is provided, and a recycle flow control valve 27 and a recycle flow detector 28 are provided as means for adjusting the supply flow rate of the oxidant.
Is provided.

In the fuel cell power plant of FIG. 4 having the above-mentioned structure, the fuel and the oxidant are supplied to each fuel cell main body 1 of each string 2 during operation. The supply flow rate is controlled as follows. First, during operation, fuel and oxidant are supplied from the fuel processing system 11 and the oxidant processing system 12 to the fuel supply common pipe 13 and the oxidant supply common pipe 14, respectively. The supply flow rates of the fuel and the oxidant are adjusted by the fuel flow control valve 15 and the fuel flow meter 16, and the oxidant flow control valve 17 and the oxidant flow meter 18, respectively. In this case, the supply flow rates of the fuel and the oxidant are adjusted based on the signal of the total current detector 4. That is, the total current detector 4 measures the load current extracted from the electric system 3 by the string 2 in the m-th column, and from the load current thus measured, the required fuel / oxidant flow rate of the entire fuel cell is measured. It can be calculated. Then, flow rate follow-up control of the supply flow rates of the fuel and the oxidant is performed so as to satisfy the required flow rate calculated in this way.

As described above, the fuel adjusted by the fuel flow control valve 15 and the fuel flow meter 16 and the oxidant adjusted by the oxidant flow control valve 17 and the oxidant flow meter 18 are
It is equally distributed to the fuel supply header 19 and the oxidant supply header 20 of each string 2 through the fuel supply common pipe 13 and the oxidant supply common pipe 14. Furthermore, each string 2
The fuel and the oxidant supplied to the fuel cell body 1 are evenly distributed to each fuel cell body 1 in each string 2. By the series of operations described above, the required amount of fuel / oxidant is supplied to each fuel cell body 1, and the fuel / oxidant utilization rate is maintained within an appropriate range.

Further, the fuel and the oxidant, which have contributed to the power generation in each fuel cell body 1, are collected through the fuel discharge header 21 and the oxidant discharge header 22 of each string 2 and the fuel discharge common pipe 23, respectively. Common piping for discharging oxidant 2
Discharged by 4. Of these, part of the oxidant discharged to the common oxidant discharge pipe 24 is recycled pipe 25.
Via the recycle blower 26 to the oxidant supply common pipe 14. Such recycling of oxidants
This is performed in order to adjust the oxygen concentration of the supplied oxidant and suppress the battery voltage within the limit value. Such a recycle flow rate is controlled as follows.

That is, a voltage detector 5 for measuring the voltage is connected to each fuel cell body 1, and the average value of the signals of all the voltage detectors 5 can be regarded as the detected voltage value of the entire fuel cell. . Therefore, the recycle blower 26 is started / stopped by comparing the battery voltage limit value and the detected voltage value, and the recycle flow rate control valve 27 and the recycle flow rate detector 28 are used to perform appropriate flow rate control.

As described above, according to the fuel cell power plant of FIG. 4, it is possible to maintain the fuel / oxidant utilization rate of each cell main body and the cell voltage within an appropriate range with a minimum amount of operation. .

[0012]

By the way, in the conventional fuel cell power generation plant as described above, there is no great difference in the characteristics of each fuel cell main body 1, and as long as the individual string current and the individual cell voltage are equal, As described above, it is possible to maintain the fuel / oxidant utilization rate of each cell body and the cell voltage within an appropriate range by the minimum operation.

However, in practice, the fuel cell body 1
The characteristic changes and attenuation of are not uniform. That is, a characteristic imbalance that cannot be ignored after long-term operation,
Also, replacing some of the fuel cell main bodies 1 may cause an extreme imbalance in characteristics. Then, in the fuel cell power generation plant of FIG. 4, when the characteristic imbalance occurs between the fuel cell main bodies 1 as described above, the imbalance between the individual string currents and the imbalance between the individual cell voltages occur. I will end up. When a uniform fuel / oxidant is supplied to each fuel cell main body 1 in such an unbalanced state, a fuel / oxidant deficiency phenomenon occurs in the fuel cell main body 1 included in the string 2 having a large string current. It can cause damage. Further, when there is a fuel cell body 1 having significantly higher characteristics than the others, the fuel cell body 1 may be exposed to an overvoltage state and may be damaged.

The present invention has been proposed in order to solve the above problems of the prior art, and its purpose is to:
Even if any characteristic imbalance occurs between the fuel cell bodies, the fuel / oxidant utilization rate of all fuel cell bodies,
It is an object of the present invention to provide a highly reliable fuel cell power generation plant capable of maintaining a cell voltage within an appropriate range.

More specifically, the object of the invention as set forth in claim 1 is to provide a fuel between the strings (series-connected battery group) even if the current values of the strings (series-connected battery group) are unbalanced. By maintaining the utilization factor uniform, the fuel utilization factors of all the fuel cell main bodies are maintained within an appropriate range. An object of the invention according to claim 2 is to maintain a uniform oxidant utilization rate between the strings (series-connected battery groups) even when the current values of the strings (series-connected battery groups) are unbalanced. Therefore, the oxidizer utilization rate of all fuel cell main bodies is maintained within an appropriate range.
It is an object of the invention according to claim 3 to prevent the fuel cell main body from being in an overvoltage state when a fuel cell main body having significantly higher characteristics than other fuel cell main bodies is present, so that the cells of all the fuel cell main bodies can be prevented. To maintain the voltage in the proper range.

[0016]

In the fuel cell power plant according to the present invention, a fuel cell body composed of a fuel electrode and an oxidizer electrode is electrically connected in series by n (n ≧ 1) to form a series-connected cell group. A fuel cell body group formed by electrically connecting the series-connected cell groups in parallel in m rows (m ≧ 2); and fuel supply means for supplying fuel to the fuel electrode of the fuel cell body group.
In a fuel cell power generation plant having an oxidant supply means for supplying an oxidant to an oxidant electrode of a fuel cell body group, a method of adjusting a supply amount of a fuel or an oxidant has a certain feature.

That is, the fuel cell power generation plant according to claim 1 is characterized by comprising a plurality of current detecting means and a plurality of fuel supply adjusting means. Of these, the current detection means is means for individually detecting the current flowing in each series-connected battery group. Then, the fuel supply adjustment means, based on the individual current detection value obtained by each current detection means,
This is means for individually adjusting the ratio of the fuel flow rate supplied to each series-connected cell group.

A fuel cell power plant according to a second aspect of the invention is characterized by comprising a plurality of current detecting means and a plurality of oxidant supply adjusting means. Of these, the current detection means is means for detecting an individual current flowing through each series-connected battery group. Then, the oxidant supply adjusting means, based on the individual current detection value obtained by each current detection means,
It is a means for individually adjusting the ratio of the flow rate of the oxidant supplied to each series-connected battery group.

Further, the fuel cell power plant according to claim 3 is characterized in that it is provided with a plurality of voltage detecting means, an oxidant recycling means, and a recycling flow rate adjusting means. Among these, the voltage detecting means is means for detecting an individual voltage of each fuel cell main body. The oxidant recycling means is means for recycling a part of the oxidant discharged after contributing to power generation in the fuel cell main body, to the upstream side of the oxidant electrode of the fuel cell main body group. The recycling flow rate adjusting means is a means for adjusting the recycling flow rate of the oxidant to be recycled to the upstream side of the oxidant electrode of the fuel cell body group based on the individual voltage detection values obtained by the voltage detecting means.

[0020]

The operation of the fuel cell power plant of the present invention having the above-mentioned structure is as follows.

First, in the invention of claim 1, an imbalance occurs in the characteristics of the fuel cell body, and as a result, a string (series-connected cell group) detected by the current detecting means.
When an imbalance occurs in the current detection value, the fuel supply adjusting means, based on these string current detection values,
The fuel flow rate to be supplied is determined by the following method.

Here, in general, the string current is I,
When the flow rate of the fuel supplied to the fuel cell body belonging to the string is F, the fuel utilization rate U in the string
_F is represented by the following formula (1).

[Equation 1] From this equation (1), it can be seen that as the string current I increases, the fuel utilization rate U _F also increases. If the fuel utilization rate U _F increases excessively, fuel shortage will occur and the fuel cell body will be damaged.

Therefore, in order to prevent such an excessive increase in the fuel utilization factor U _F , the fuel flow rate F to be supplied is determined in accordance with the ratio between the string currents I. That is,
m each string S ₁ of the individual, S _2, ..., and supplies the string current flowing through _{S m I 1, I 2,} ..., when the I _m, the string S _1, S _2, ..., to S _m The fuel flow rates F ₁ , F ₂ , ..., F _m are determined by the following equation (2).

## EQU2 ## F ₁ : F ₂ ...: F _m = I ₁ : I ₂ ...: I _m
Formula (2) Then, the fuel supply adjusting means is configured so that each string S ₁ ,
S _2, ..., each fuel flow rate fuel flow rate supplied to S _m is determined as described above respectively _{F 1, F 2, ...,} F m
Adjust so that By adjusting such a supply fuel flow, each string S _1, S _2, ..., even if there is unbalance between the battery current within the S _m, each string S _1, S _2, ..., between S _m The fuel utilization rate becomes uniform.

Next, in the invention of claim 2, when an imbalance occurs in the characteristics of the fuel cell main body, resulting in an imbalance in the string current value detected by the current detecting means, the oxidant supply is performed. The adjusting means determines the supplied oxidant flow rate by the following method based on these string current detection values.

Here, in general, the string current is I,
When the flow rate of the oxidant supplied to the fuel cell main body belonging to the string is G, the oxidant utilization rate U _A in the string is expressed by the following equation (3).

(Equation 3) From this equation (3), it can be seen that as the string current I increases, the oxidant utilization rate U _A also increases. If the oxidant utilization rate U _A is excessively increased, the oxidant deficiency is caused and the fuel cell main body is damaged.

Therefore, in order to prevent such an excessive increase in the oxidant utilization rate U _A , the oxidant flow rate G to be supplied is determined in accordance with the ratio between the string currents I. In other words, each string S _1, S ₂ of m, ..., I _1, I ₂ the current flowing through the S _m, ..., when the I _m, the string S _1, S _2, ..., supplied to S _m Fuel flow rate G ₁ ,
G ₂ , ..., G _m are determined by the following equation (4).

## EQU4 ## G ₁ : G ₂ ...: G _m = I ₁ : I ₂ ...: I _m Equation (4) Then, the oxidant supply adjusting means is provided for each string S ₁ , S.
_2, ..., oxidizer flow rate supplied to S _m is the oxidizing agent flow rate G _1, G _2, which is determined as described above respectively, ..., G
Adjust to _m . By adjusting such a supply oxidizing agent flow, each string S _1, S _2, ..., even if there is unbalance between the battery current within the S _m, each string S _1, S _2, ..., between S _m The utilization rate of the oxidant becomes uniform.

Next, in the invention of claim 3, when there is a fuel cell main body having a remarkably high voltage (remarkably high characteristics compared to the other) due to replacement of the fuel cell main body or the like, voltage detection is performed. Based on the individual voltage detection value by the means, the recycling flow rate adjusting means increases the recycling flow rate of the oxidizer so that the voltage of the fuel cell body with the highest voltage value among all the fuel cell bodies is within the limit value. Let By adjusting the recycling flow rate of the oxidant as described above, it is possible to prevent the fuel cell main body having the highest characteristics from becoming overvoltage.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a configuration diagram showing an embodiment of a fuel cell power generation plant according to the present invention. In FIG. 1, parts common to those of the conventional example shown in FIG. 4 are designated by the same reference numerals, and description thereof will be omitted. The present embodiment is different from the conventional example of FIG. 4 in that each string 2 is individually connected with a string current detector 31 for detecting a string current flowing in the string 2, and the fuel supply header 19 of each string 2 is connected. A fuel supply damper 32 and an oxidant supply damper 33 are provided on the oxidant supply header 20. In this case, the string current detector 31
Corresponds to the current detection means according to claim 1 or 2. Further, the fuel supply damper 32 adjusts the opening degree thereof based on the individual string current detection value obtained by each string current detector 31, thereby individually adjusting the ratio of the fuel flow rate supplied to each string 2. Means, which corresponds to the fuel supply adjusting means according to claim 1. Further, the oxidant supply damper 33 adjusts the opening degree based on the individual string current detection value obtained by each string current detector 31 to adjust the ratio of the oxidant flow rate supplied to each string 2. It is a means for individually adjusting and corresponds to the oxidant supply adjusting means according to claim 2. In this case, the fuel supply damper 32 and the oxidant supply damper 33 are the same as those shown in FIG.
4 is controlled.

That is, as shown in FIG.
4 includes a flow rate distribution calculator 35 and an opening degree calculator 36. Of these, the flow rate distribution calculator 35 is connected to each string current detector 31, and calculates the flow rate distribution of the fuel supplied to each string 2 from the individual string current detection values obtained from each string current detector 31. Is configured to. Specifically, each string S
_The string currents flowing in ₁ , S ₂ , ..., S _m are I ₁ , I
₂ , ..., I _m , each string S ₁ , S ₂ ,
,, _Sm , the fuel flow rate F ₁ , F ₂ , ..., F _m
It is configured to be obtained by the following equation (5).

[Formula 5] F ₁ : F ₂ ...: F _m = I ₁ : I ₂ ...: I _m (Equation 5) Then, the opening degree calculator 36 is connected to the flow rate distribution calculator 35, and the flow rate distribution calculator 35 is connected. each string obtained by the arithmetic unit _{35 (S 1, S 2,} ..., S m) 2 of each string from the flow _{(S 1, S 2, ...} , S m) the opening of 2 of each fuel supply damper 32 A control command is sent to each fuel supply damper 32 according to the calculated opening.

Although the fuel control side of the control device 34 has been described above, the oxidant control side has the same structure. That is, although not shown, the control device 34 also includes a flow rate distribution calculator and an opening degree calculator similar to the flow rate distribution calculator 35 and the opening degree calculator 36 on the fuel control side on the oxidant control side. There is.

Further, the control device 34 is provided with a maximum value calculator 37 and a calculator 38 for recycling the oxidant. Of these, the maximum value calculator 37 is connected to each voltage detector 5, and is configured to obtain the maximum value from the individual voltage detection values obtained from each voltage detector 5. Then, the calculator 38, based on the maximum voltage detection value obtained by the maximum value calculator 37, has the maximum voltage detection value, that is, the fuel cell main body having the highest voltage value among all the fuel cell main bodies 1. The recycle flow rate of the oxidant is determined so that the voltage value of 1 is within a predetermined limit value. Further, the calculator 38 determines the start / stop of the recycle blower 26 and the opening degree of the recycle flow control valve 27 based on the determined recycle flow rate, and controls the recycle blower 26 and the recycle flow control valve 27 according to this determination. It is configured to send a command. In this case, the voltage detector 5 corresponds to the voltage detecting means described in claim 3. Further, the recycle pipe 25 and the recycle blower 26 correspond to the oxidizing agent recycle means described in claim 3. Further, the recycle flow control valve 27 adjusts the opening degree according to the opening degree determined by the control device 34 based on the individual voltage detection value obtained by each voltage detector 5, and the upstream side of the cathode of the string 2 is controlled. It is a means for adjusting the recycling flow rate of the oxidizing agent recycled to the side, and corresponds to the recycling flow rate adjusting means according to claim 3.

Next, the operation of the fuel cell power plant according to this embodiment will be described. First, when there is no difference in the characteristics of the individual fuel cell bodies 1 immediately after construction, since all the fuel cell bodies 1 show substantially the same voltage for the same load current, the string current value flowing in each string 2 also It is almost the same. Therefore, the flow rates of the fuel and the oxidant supplied to each string 2 may be the same for all strings 2. Therefore, for both the fuel and the oxidant, only the common fuel flow rate control valve 15 and the oxidant flow rate control valve 17 provided in the oxidant supply common pipe 14 of the fuel supply common pipe 13 are collectively used for all the strings 2. The supply flow rate may be adjusted. Then, the fuel supply damper 32 and the oxidant supply damper 33 provided on the fuel supply header 19 and the oxidant supply header 20 of each string 2 are
All may be fully opened or equally opened.

However, after a certain period of operation, the characteristics of the fuel cell body 1 will inevitably vary, and the voltage indicated by the fuel cell body 1 will differ for the same load current. In this case, since the strings 2 are connected in parallel, the voltages of the strings 2 are all equal, and the difference in the characteristics of the fuel cell body 1 as described above appears as a difference in the string current. This phenomenon is apparent from the current / voltage characteristics of the battery, but will be briefly described below.

First, FIG. 3 shows a typical current of a fuel cell.
It is a graph which shows a voltage characteristic. Line A in the figure shows the initial state of the battery characteristics, and line B shows the state in which the battery characteristics have dropped from this initial state. When variations occur in the battery characteristics as shown in A and B, since the strings 2 have the same voltage as described above, the operating point of the battery whose characteristics have deteriorated to the state B is that of the initial state A. The current will drop from point C to point D in state B. Therefore, as the difference in characteristics increases, the difference in string current also increases.

On the other hand, in this embodiment, when the difference between the string currents of the respective strings 2 increases, the difference between these string currents is first detected by the individual string current detection values from the respective string current detectors 31. It will be obtained as the difference of. Next, the flow rate distribution calculator 35 of the control device 34 determines the flow rate distribution of the fuel supplied to each string 2 from the string current detection values having such a difference. Then, the opening degree of each fuel supply damper 32 of each string 2 is obtained by the opening degree calculator 36 from the fuel flow rate distribution thus obtained, and the opening degree of each fuel supply damper 32 is automatically calculated. Controlled. As a result, each fuel supply damper 32 adjusts the flow rate of fuel supplied to each string 2, and maintains the fuel utilization rate between each string 2 uniformly. Similarly, the control device 3
The opening degree of each oxidant supply damper 33 of each string 2 is obtained by the flow rate distribution calculator and the opening degree calculator on the oxidant control side of No. 4, and the opening degree of each oxidizer supply damper 33 is automatically controlled. It As a result, the flow rate of the oxidant supplied to each string 2 is adjusted by each oxidant supply damper 33, and the oxidant utilization ratio between the strings 2 is maintained uniform.

On the other hand, after a long period of operation, some of the plurality of fuel cell bodies 1 may be replaced. At this time, the replaced fuel cell bodies 1 show extremely high voltage. There are cases. In this case, if the recycling flow rate of the oxidizer is determined by the average value of all the battery voltages as in the conventional example, the battery voltage of the existing fuel cell body 1 having a long usage time shows an appropriate value, but it is replaced. The new fuel cell body 1 will be exposed to the overvoltage condition. On the other hand, in this embodiment, the recycle flow rate of the oxidant can be determined by using the maximum value of all the battery voltages instead of the average value of the battery voltage of the control device 34. However, some fuel cell bodies are not exposed to overvoltage conditions.

That is, in the present embodiment, when there is a fuel cell main body 1 having a significantly higher voltage than others (remarkably better characteristics than others), first, each voltage detection of each fuel cell main body 1 is performed. Based on the individual voltage detection value obtained by the device 5, the maximum value calculator 37 of the control device 34 obtains the maximum voltage detection value. Next, the calculator 38 determines the recycle flow rate of the oxidizer so that the maximum voltage detection value obtained by the maximum value calculator 37 is within a predetermined limit value. Subsequently, the recycle blower 2 is operated by the calculator 38 based on the determined recycle flow rate.
The start / stop of No. 6 and the opening of the recycle flow control valve 27 are determined, and the start / stop of the recycle blower 26 and the opening of the recycle flow control valve 27 are automatically controlled according to this determination. As a result, the recycle flow rate control valve 27 can adjust the recycle flow rate of the oxidant to be recycled to the upstream side of the cathode of the string 2 through the recycle pipe 25. It is possible to prevent the situation.

As described above, according to this embodiment,
Even if the current values of the strings 2 are unbalanced, the fuel utilization rate and the oxidant utilization rate between the strings 2 can be maintained uniformly, so that the fuel utilization rates and the oxidation rates of all the fuel cell main bodies 1 can be maintained. The agent utilization rate can be maintained within an appropriate range. Further, according to the present embodiment, when there is a fuel cell main body 1 having significantly higher characteristics than others due to replacement of the fuel cell main body 1 or the like, the fuel cell main body 1 having the highest characteristics is in an overvoltage state. By preventing this, it is possible to maintain the cell voltage of all the fuel cell main bodies 1 in an appropriate range.

The present invention is not limited to the above-mentioned embodiment, but the concrete constitution of each part can be changed appropriately. For example, the number of fuel cell main bodies forming a string can be appropriately selected, and the number of strings can also be appropriately selected. On the other hand, specific configurations such as current detection means, voltage detection means, fuel supply adjustment means, oxidant supply adjustment means, and recycle flow rate adjustment means, and specific configurations of the control system of each of these means can be selected as appropriate. Is.

[0040]

As described above, according to the present invention,
Current detecting means and fuel supply adjusting means or oxidant supply adjusting means are individually provided for each series-connected battery group, or recycle flow rate adjusting means is based on the individual voltage detection values obtained by each voltage detecting means. By adjusting the recycle flow rate of oxidizer, the fuel / oxidant utilization rate and cell voltage of all fuel cell bodies can be maintained within an appropriate range regardless of any characteristic imbalance between the fuel cell bodies. It is possible to provide a highly reliable fuel cell power generation plant.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a fuel cell power plant according to the present invention.

FIG. 2 is a configuration diagram showing a control device of the fuel cell power plant of FIG.

FIG. 3 is a graph showing standard current / voltage characteristics of a fuel cell.

FIG. 4 is a configuration diagram showing an example of a conventional fuel cell power generation plant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel cell main body 2 ... String 3 ... Electric system 4 ... Total current detector 5 ... Voltage detector 11 ... Fuel processing system 12 ... Oxidizing agent processing system 13 ... Fuel supply common piping 14 ... Oxidizing agent supply common piping 15 ... Fuel Flow control valve 16 ... Fuel flow meter 17 ... Oxidizer flow control valve 18 ... Oxidizer flow meter 19 ... Fuel supply header 20 ... Oxidizer supply header 21 ... Fuel discharge header 22 ... Oxidizer discharge header 23 ... Fuel discharge common pipe 24 Common oxidizer discharge pipe 25 Recycle pipe 26 Recycle blower 27 Recycle flow control valve 28 Recycle flow detector 31 String current detector 32 Fuel supply damper 33 Oxidant supply damper 34 Control unit 35 Flow rate Distribution calculator 36 ... Opening calculator 37 ... Maximum value calculator 38 ... Calculator

Claims (3)

[Claims] 1. A series-connected cell group is formed by electrically connecting n (n ≧ 1) fuel cell bodies each consisting of a fuel electrode and an oxidizer electrode in series, and the series-connected cell group is electrically parallel. A fuel cell body group connected in m columns (m ≧ 2), fuel supply means for supplying fuel to the fuel electrode of the fuel cell body group, and oxidant for the oxidant electrode of the fuel cell body group. In a fuel cell power plant having an oxidant supply means, a plurality of current detection means for individually detecting the current flowing in each of the series-connected cell groups, and based on the individual current detection values obtained by the current detection means And a plurality of fuel supply adjusting means for individually adjusting the ratio of the fuel flow rate supplied to each of the series-connected cell groups. 2. A fuel cell main body comprising a fuel electrode and an oxidizer electrode is electrically connected in series by n (n ≧ 1) to form a series connected battery group, and the series connected battery group is electrically parallel. A fuel cell body group connected in m columns (m ≧ 2), fuel supply means for supplying fuel to the fuel electrode of the fuel cell body group, and oxidant for the oxidant electrode of the fuel cell body group. In a fuel cell power plant having an oxidant supply means, a plurality of current detection means for detecting individual currents flowing in each of the series-connected cell groups, and based on the individual current detection values obtained by the current detection means And a plurality of oxidant supply adjusting means for individually adjusting the ratio of the flow rate of the oxidant supplied to each of the series-connected battery groups. 3. A series-connected battery group is formed by electrically connecting n (n ≧ 1) fuel cell bodies each including a fuel electrode and an oxidizer electrode in series, and the series-connected battery group is electrically parallel. A fuel cell body group connected in m columns (m ≧ 2), fuel supply means for supplying fuel to the fuel electrode of the fuel cell body group, and oxidant for the oxidant electrode of the fuel cell body group. In the fuel cell power generation plant having the oxidant supply means for operating, a plurality of voltage detection means for detecting the individual voltage of each of the fuel cell main bodies, and one of the oxidizers discharged after contributing to power generation in the fuel cell main body. A portion of the oxidant electrode of the fuel cell body group, which is recycled to the upstream side of the oxidant electrode of the fuel cell body group, based on the individual voltage detection values obtained by the voltage detection means. Acid recycled to the upstream side A fuel cell power plant, comprising: a recycle flow rate adjusting means for adjusting a recycle flow rate of the agent.