JP3312499B2 - Fuel cell generator - Google Patents

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 generator.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generators, such as high efficiency and little impact on the environment. They are attracting attention as power generation systems following hydro, thermal and nuclear power. And research is being conducted in various countries around the world.

FIG. 9 shows an example of a molten carbonate fuel cell power generator using natural gas as fuel. As shown in the figure, a power generator includes a reformer 3 for reforming a fuel gas 1 in which natural gas and steam are mixed into an anode gas 2 containing hydrogen, a cathode gas 4 containing oxygen, and the anode gas 2.
And a fuel cell 5 for generating electricity from the fuel cell 5. The anode gas 2 produced by the reformer 3 is supplied to the anode An of the fuel cell 5. 6, and is supplied to the combustion chamber Co of the reformer 3 as combustion gas by the anode exhaust gas line 7. Note that the fuel cell 5 is stored in the storage container 8 to prevent flammable gas and the like from leaking to the outside to enhance safety.

The reformer 3 burns combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 6 leaving the fuel cell 5 and a part of the cathode exhaust gas 9 to produce a high-temperature combustion exhaust gas 10. A combustion chamber Co is formed, and a reforming chamber Re filled with a reforming catalyst to reform the fuel gas 1 by heat transfer from the combustion chamber Co. The high-temperature anode gas 2 containing hydrogen is cooled through the fuel heater 11 and supplied to the anode An of the fuel cell 5. On the other hand, the combustion exhaust gas 10 whose temperature has been lowered by the heat radiation is cooled by an air preheater 13 through an exhaust gas supply line 12, moisture is removed by a steam separator drum 15 through a condenser 14, and pressurized by a low-temperature blower 16, The air is mixed with the air 17, heated by the air preheater 13, and enters the cathode circulation line 18.

The cathode gas 4 partially reacts with the cathode Ca of the fuel cell 5 to become a high-temperature cathode exhaust gas 9,
After the power is recovered by being guided to the turbine T of the turbine compressor 21 for compressing the air 17 by the cathode exhaust gas line 34, the steam 2 is further recovered by the steam generator 22 to recover exhaust heat.
3 is generated and discharged out of the system. The steam 23 is sent to a fuel gas supply line 25 by a steam line 24 and mixed with a source gas 26 such as a natural gas sent from a source blower 27 to become a fuel gas 1 and a reformer 3
Is supplied to the reforming chamber Re.

A part of the cathode exhaust gas 9 of the fuel cell 5 is supplied to the air preheater 13 by a cathode circulation line 18.
And is circulated and supplied as cathode gas 4 to the cathode Ca of the fuel cell 5 by the high-temperature blower 28.

The air 17 compressed by the air compressor C of the turbine compressor 21 joins the exhaust gas 10 from which the moisture has been removed at the outlet of the low-temperature blower 16. The turbine compressor 21 is provided with a bypass line 30 having an air blower 29.
The air blower 29 is used as a backup when the capacity of the air 17 compressed by the air compressor C becomes insufficient.

That is, the air blower 29 is connected to the fuel cell 5
Even when the flow rate of the cathode exhaust gas 9 sent to the turbine compressor 21 is low, such as during low load operation including the start-up of the air, the air 1
In order to satisfy the required quantity of 7, the air compressor C is operated so as to compensate for the shortage.

In FIG. 9, a fuel supply valve 31 is provided at an outlet of a raw material blower 27, and a fuel gas supply line 25 on the outlet side of the fuel supply valve 31 has an N ₂ gas purge having an N ₂ supply valve 32. Line 33 is connected.

On the other hand, an exhaust gas supply line 12 downstream of the air preheater 13 is provided with a combustion chamber C of the reformer 3.
An oxygen concentration detector 60 for detecting an oxygen concentration 64 contained in the combustion exhaust gas 10 discharged from the fuel cell 10 is provided. And a rotation speed command 65 to the low-temperature blower 16 based on an output command 63 to the fuel cell 5, and the output command 63 and the oxygen concentration detector 60. A controller 62 for outputting an opening degree correction command 66 to the reformer combustion air flow rate control valve 61 based on the oxygen concentration 64 detected by the control unit 62 is provided.
It should be noted that the oxygen concentration detector 60 is not provided at the outlet of the combustion chamber Co of the reformer 3 because the temperature of the combustion exhaust gas 10 is high at the outlet of the combustion chamber Co of the reformer 3 and the oxygen concentration 64 is not suitable for the detection of the air preheater 13
The oxygen concentration detector 60 is provided in the exhaust gas supply line 12 downstream of the air preheater 13 in order to detect the oxygen concentration 64 in the combustion exhaust gas 10 after the temperature has decreased to some extent due to heat exchange through the air. ing.

As shown in FIG. 10, the controller 62 outputs a rotation speed command 65 of the low-temperature blower 16 to the low-temperature blower 16 through an automatic / manual switch 67 based on an output command 63 to the fuel cell 5. A generator 68 and a function generator 7 for outputting a preceding opening command 69 for the reformer combustion air flow control valve 61 based on an output command 63 for the fuel cell 5.
0 and a function generator 7 for outputting an oxygen concentration command 71 in the flue gas 10 based on an output command for the fuel cell 5
2 and the oxygen concentration 6 detected by the oxygen concentration detector 60
4 and an oxygen concentration command 71 output from the function generator 72, and a subtractor 74 for outputting an oxygen concentration deviation 73; and an oxygen concentration deviation 73 output from the subtractor 74.
A function generator 76 that outputs an opening degree correction command 75 for the reformer combustion air flow rate control valve 61 based on the above, and an opening degree correction command 75 output from the function generator 76 is proportionally integrated and a signal 77 is output. A proportional-integral adjuster 78, a signal 77 output from the proportional-integral adjuster 78, and the function generator 70
Of the reformer combustion air flow control valve 61 via an automatic / manual switch 79 to the reformer combustion air flow control valve 61. And an output adder 80.

A function as shown in FIG. 3 is input to the function generator 68. The function is substantially proportional to the increase and decrease of the output command 63, and the rotational speed command 65 of the low-temperature blower 16 is provided. Is increased or decreased. A function as shown in FIG. 4 is input to the function generator 70, and the function is provided in proportion to the increase or decrease of the output command 63 in advance of the reformer combustion air flow control valve 61. Opening command 6
9 is increased or decreased. A function as shown in FIG. 5 is input to the function generator 72. The function increases or decreases the oxygen concentration command 71 in the flue gas 10 in substantially proportion to the increase or decrease of the output command 63. It means to make it. Further, a function as shown in FIG. 6 is input to the function generator 76, and the function is substantially proportional to the increase or decrease of the oxygen concentration deviation 73, and the function of the reformer combustion air flow control valve 61 is adjusted. This indicates that the opening degree correction command 75 is increased or decreased.

Thus, during operation of the fuel cell power generator as described above, the output command 63 to the fuel cell 5 is output.
Is input to the controller 62 and the oxygen concentration detector 60
Thereby, the oxygen concentration 64 contained in the combustion exhaust gas 10 discharged from the combustion chamber Co of the reformer 3 is detected, and the oxygen concentration 64 is input to the controller 62.

When an output command 63 for the fuel cell 5 is input to the function generator 68 of the controller 62, the function generator 68 outputs the low-temperature blower 1 based on the output command 63.
6 is obtained, the rotation number command 65 is output to the low-temperature blower 16 via the automatic / manual switch 67, and the rotation number of the low-temperature blower 16 is controlled based on the output instruction 63. .

When the output command 63 is input to the function generator 70, the function generator 70 determines the preceding opening command 69 of the reformer combustion air flow control valve 61 based on the output command 63. , The preceding opening degree command 69 is
Is output to the reformer combustion air flow control valve 61 via the automatic / manual switch 79, and is output to the reformer combustion air flow control valve 61.
Is controlled in advance based on the output command 63 so that there is no response delay, and when the output command 63 is input to the function generator 72, the output command 63 is output from the function generator 72. The oxygen concentration command 71 in the flue gas 10 is obtained based on the
4 and the oxygen concentration 64 in the flue gas 10 detected by the oxygen concentration detector 60 is output to the subtractor 74, and the difference between the oxygen concentration command 71 and the oxygen concentration 64 is obtained in the subtractor 74. The oxygen concentration deviation 73 is output to the function generator 76, and the function generator 76 obtains the opening correction command 75 of the reformer combustion air flow rate control valve 61 based on the oxygen concentration deviation 73, and the proportional integration controller 78, the proportionality-integral adjuster 78 performs the proportional-integral processing on the opening correction command 75, and outputs a signal 77 to the adder 80. The adder 80 compares the preceding opening-degree command 69 with the signal 77. The opening degree correction command 66 is output to the reformer combustion air flow control valve 61 via an automatic / manual switch 79, and the opening degree of the reformer combustion air flow control valve 61 is output command 63. And fire It is adjusted based on the oxygen concentration 64 in the exhaust gas 10.

As a result, the amount of the cathode exhaust gas 9 introduced into the combustion chamber Co of the reformer 3 is adjusted by adjusting the suction amount of the combustion exhaust gas 10 by controlling the rotation speed of the low-temperature blower 16, and the reforming is performed. Powder combustion air flow control valve 6
By adjusting the opening degree of 1, the discharge amount of the low-temperature blower 16 is adjusted, and the flow rate of air supplied to the combustion chamber Co of the reformer 3 is adjusted.

[0017]

In the fuel cell power generator as described above, when the output command 63 for the fuel cell 5 changes, especially when the output decreases, the fuel cell 5 is not affected by a delay in the control system.
The unburned portion of the fuel gas not consumed by the anode An temporarily increases and is supplied to the combustion chamber Co of the reformer 3, and the temperature of the combustion chamber Co may become abnormally high.

However, in the case of the conventional fuel cell power generator, as described above, the rotation speed of the low-temperature blower 16 is uniformly controlled based on the output command 63 of the fuel cell 5, and the combustion of the reformer 3 is performed. It was impossible to decrease the temperature of the combustion chamber Co by increasing the flow rate of the air supplied to the chamber Co, and there was a disadvantage that the operation was stopped due to an abnormal rise in the temperature of the combustion chamber Co.

The present invention has been made in view of such circumstances, and the fuel cell 5
It is an object of the present invention to provide a fuel cell power generator capable of preventing an abnormal rise in the temperature of the combustion chamber Co of the reformer 3 when the output of the fuel cell decreases, and preventing the operation from being stopped.

[0020]

According to the present invention, a cathode Ca is provided.
And a fuel cell 5 for generating electricity, and a fuel gas 1 obtained by adding steam 23 to a raw material gas 26 is reformed into an anode gas 2 containing hydrogen and supplied to the anode An of the fuel cell 5 The reforming chamber Re, the anode exhaust gas 6 discharged from the anode An of the fuel cell 5 and the fuel cell 5
And a combustion chamber Co for generating a heat for reforming in the reforming chamber Re by introducing a part of the cathode exhaust gas 9 discharged from the cathode Ca. And a turbine T driven by a cathode exhaust gas 9 discharged from a cathode Ca of the fuel cell 5, and supplies air 17 from an air compressor C driven by the turbine T to the cathode Ca of the fuel cell 5. The amount of the cathode exhaust gas 9 introduced into the combustion chamber Co of the reformer 3 is adjusted by adjusting the suction amount by the turbine compressor 21 and the rotation speed control. A low-temperature blower 16 for supplying the combustion exhaust gas 10 to the combustion chamber Co of the reformer 3 via the cathode Ca of the fuel cell 5 together with the air 17 from the air compressor C of the turbine compressor 21; B A fuel cell power generator including a reformer combustion air flow control valve 61 that is provided on the outlet side of the water 16 and controls the air flow to the combustion chamber Co of the reformer 3. A function generator 70 for outputting a preceding opening command 69 of the reformer combustion air flow control valve 61 based on the output command 63, and an output command 6 for the fuel cell 5
A function generator 72 for outputting an oxygen concentration command 71 in the flue gas 10 based on the fuel cell 3 and an oxygen concentration detector for detecting the oxygen concentration 64 contained in the flue gas 10 discharged from the combustion chamber Co of the reformer 3 60, an oxygen concentration command 71 output from the function generator 72, and the oxygen concentration detector 60
A subtractor 74 for obtaining a difference from the oxygen concentration 64 detected in step S1 and outputting an oxygen concentration deviation 73, and opening the reformer combustion air flow control valve 61 based on the oxygen concentration deviation 73 output from the subtractor 74. Function generator 76 for outputting degree correction command 75
A temperature detector 81 for detecting an outlet temperature 82 of the combustion chamber Co of the reformer 3; and a signal generator 84 for setting and outputting an upper limit 83 of the outlet temperature 82 of the combustion chamber Co of the reformer 3.
And an outlet temperature 82 detected by the temperature detector 81;
A subtractor 86 for obtaining a difference from an upper limit value 83 output from the signal generator 84 and outputting an outlet temperature deviation 85, and a reformer combustion air flow rate based on the outlet temperature deviation 85 output from the subtractor 86 A function generator 88 for outputting an opening correction command 87 for the control valve 61, a signal generator 90 for setting and outputting an allowable maximum opening 89 of the reformer combustion air flow rate control valve 61, and an output from the function generator 88. Opening degree correction command 87
A proportional-integral adjuster 92 with a limiter that outputs a signal 91 by performing a proportional-integral process so as not to exceed the allowable maximum opening 89 output from the signal generator 90, and a signal output from the proportional-integral adjuster 92 with the limiter 91 and the function generator 7
6, an adder 93 for obtaining the sum of the opening correction command 75 output from the controller 6 and outputting an opening correction command 75 'for the reformer combustion air flow control valve 61, and an opening output from the adder 93. A proportional-integral adjuster 78 that outputs a signal 77 ′ by performing a proportional-integral process on the correction command 75 ′, a signal 77 ′ output from the proportional-integral adjuster 78, and a leading opening output from the function generator 70. An adder 80 for obtaining the sum of the command 69 and an opening correction command 66 ′ for the reformer combustion air flow control valve 61 to the reformer combustion air flow control valve 61, and an output command 63 for the fuel cell 5. And a function generator 68 for outputting a rotational speed command 65 of the low-temperature blower 16 based on the low-temperature blower 1 based on the opening correction command 66 ′ output from the adder 80.
A function generator 95 for outputting a rotation speed correction command 94 of No. 6;
When the rotation speed correction command 94 output from the function generator 95 changes, a change rate limiter 97 that outputs a rotation speed correction command 96 by performing processing for limiting the rate of change to a range equal to or less than a set value. When the outlet temperature 82 of the combustion chamber Co of the reformer 3 is equal to or lower than the upper limit value 83, the rotational speed command 65 output from the function generator 68 is output as it is to the low-temperature blower 16 as the command 65 '. When the outlet temperature 82 of the combustion chamber Co of the reformer 3 exceeds the upper limit 83, the rotation speed correction command 96 output from the function generator 95 via the rate-of-change limiter 97 is set as a command 65 ', and the low-temperature blower 16 is used.
And a switch 98 for outputting the data to the

[0021]

Therefore, during operation of the fuel cell power generator, an output command 63 for the fuel cell 5 is input to the controller 62, and the reformer 3 is controlled by the oxygen concentration detector 60.
The oxygen concentration 64 contained in the combustion exhaust gas 10 discharged from the combustion chamber Co of the reformer 3 is detected by the temperature detector 81 and the outlet temperature 82 of the combustion chamber Co of the reformer 3 is detected. The temperature 82 is input to the controller 62 '.

When an output command 63 for the fuel cell 5 is input to a function generator 70 of a controller 62 ', the function generator 70 precedes the reformer combustion air flow control valve 61 based on the output command 63. An opening command 69 is obtained, and the preceding opening command 69 is output to the reformer combustion air flow control valve 61 via the adder 80, and the opening of the reformer combustion air flow control valve 61 is determined by the output. Based on the command 63, it is controlled in advance so that there is no response delay.
3 is input to the function generator 72 of the controller 62 ', the function generator 72 obtains an oxygen concentration command 71 in the flue gas 10 based on the output command 63, and the oxygen concentration command 71 is subtracted by the subtractor. The oxygen concentration 64 in the flue gas 10 output to the exhaust gas 74 and detected by the oxygen concentration detector 60 is output to the subtractor 74, and the difference between the oxygen concentration command 71 and the oxygen concentration 64 is calculated in the subtractor 74. The oxygen concentration deviation 73 is output to the function generator 76, and the function generator 76
In step (1), an opening correction command 75 for the reformer combustion air flow rate control valve 61 is obtained based on the oxygen concentration deviation 73, and is output to the adder 93.

When the outlet temperature 82 detected by the temperature detector 81 is input to the subtractor 86 of the controller 62 ', the outlet temperature 82 and the output of the signal generator 84 are set in the subtractor 86. The difference between the outlet temperature 82 of the combustion chamber Co of the porcelain 3 and the upper limit value 83 is determined, and an outlet temperature deviation 85 is output to a function generator 88. The function generator 88 performs reforming based on the outlet temperature deviation 85. The opening correction command 87 of the reformer combustion air flow control valve 61 is obtained, and from the signal generator 90 to the limiter proportional integral controller 92 to which the allowable maximum opening 89 of the reformer combustion air flow control valve 61 is input. The opening correction command 87 is proportionally integrated by the limiter-equipped proportional-integral adjuster 92, and a signal 91 is output from the adder 93.
The adder 93 calculates the sum of the signal 91 and the opening correction command 75 of the reformer combustion air flow control valve 61, and corrects the opening of the reformer combustion air flow control valve 61. The command 75 'is output to the proportional-integral adjuster 78. The proportional-integral adjuster 78 performs the proportional-integral processing on the opening correction command 75', and outputs the signal 77 'to the adder 80. The sum of the preceding opening command 69 and the signal 77 is obtained, an opening correction command 66 'is output to the reformer combustion air flow control valve 61, and the opening of the reformer combustion air flow control valve 61 is output. It is adjusted based on the command 63, the oxygen concentration 64 in the flue gas 10 and the outlet temperature 82 of the combustion chamber Co of the reformer 3.

On the other hand, an output command 6 for the fuel cell 5
3 is input to the function generator 68 of the controller 62 ', the function generator 68 determines the rotational speed command 65 of the low-temperature blower 16 based on the output command 63, and
When the outlet temperature 82 of the combustion chamber Co is equal to or lower than the upper limit value 83, the rotation speed command 65 is output from the switch 98 as it is to the low temperature blower 16 as the command 65 ', and the rotation speed of the low temperature blower 16 is output to the output command 63. Is controlled based on the

The opening correction command 66 'output from the adder 80 is input to a function generator 95, and the function generator 95 controls the low-temperature blower 16 based on the opening correction command 66'. A rotation speed correction command 94 is obtained and output to the change rate limiter 97. The change rate limiter 97 performs a process of limiting the change rate of the rotation speed correction command 94 to a range equal to or less than a set value. The number correction command 96 is output to the switch 98. In this state, when the output temperature 82 of the combustion chamber Co of the reformer 3 exceeds the upper limit 83, for example, when the output of the fuel cell 5 decreases, Instead of the rotation speed command 65, a rotation speed correction command 96 output from the function generator 95 via the change rate limiter 97 is output from the switch 98 as a command 65 '.
Is output to the low-temperature blower 16, and the rotation speed of the low-temperature blower 16 is controlled in accordance with the opening correction command 66 ′ of the reformer combustion air flow control valve 61.

As a result, when the outlet temperature 82 of the combustion chamber Co of the reformer 3 exceeds the upper limit value 83, the opening of the reformer combustion air flow control valve 61 does not exceed the allowable maximum opening 89. And the rotation speed of the low-temperature blower 16 is increased at a desired rate in accordance with the opening of the reformer combustion air flow control valve 61 and supplied to the combustion chamber Co of the reformer 3. The temperature of the combustion chamber Co is reduced to a required temperature equal to or lower than the upper limit value 83 and is maintained.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIGS. 9 and 10 represent the same components, and the basic structure is shown in FIG. And FIG.
This embodiment is the same as the conventional one shown in FIG. 1 except that, as shown in FIGS. 1 and 2, the exhaust gas supply line 12 at the outlet of the combustion chamber Co of the reformer 3 is A temperature detector 81 for detecting an outlet temperature 82 of the combustion chamber Co of the fuel cell 3, an output command 63 for the fuel cell 5, an oxygen concentration 64 detected by the oxygen concentration detector 60, and an outlet detected by the temperature detector 81. Based on the temperature 82, a controller 62 'for outputting a rotational speed command 65' to the low-temperature blower 16 and outputting an opening correction command 66 'to the reformer combustion air flow control valve 61 is provided. .

As shown in FIG. 2, the controller 62 ′ includes a function generator 70 for outputting a preceding opening command 69 for the reformer combustion air flow rate control valve 61 based on an output command 63 for the fuel cell 5, A function generator 72 for outputting an oxygen concentration command 71 in the flue gas 10 based on an output command 63 to the fuel cell 5, an oxygen concentration command 71 output from the function generator 72, and detection by the oxygen concentration detector 60. A difference between the calculated oxygen concentration 64 and a subtractor 74 that outputs an oxygen concentration deviation 73, and an opening correction of the reformer combustion air flow control valve 61 based on the oxygen concentration deviation 73 output from the subtractor 74. A function generator 76 that outputs a command 75 and an upper limit value 83 (about 800) of the outlet temperature 82 of the combustion chamber Co of the reformer 3
C), an output temperature 82 detected by the temperature detector 81, and a signal generator 84
A subtractor 86 for obtaining a difference from an upper limit value 83 outputted from the subtractor 86 and outputting an outlet temperature deviation 85, and opening the reformer combustion air flow control valve 61 based on the outlet temperature deviation 85 outputted from the subtracter 86. Function generator 88 for outputting degree correction command 87
And the maximum allowable opening 89 of the reformer combustion air flow control valve 61.
A signal generator 90 for setting and outputting
Is output from the signal generator 9
A proportional-integral adjuster 92 with a limiter that outputs a signal 91 by performing a proportional-integral process so as not to exceed an allowable maximum opening 89 output from 0, a signal 91 output from the proportional-integral adjuster 92 with a limiter, An adder 93 that obtains the sum with the opening correction command 75 output from the function generator 76 and outputs the opening correction command 75 ′ for the reformer combustion air flow control valve 61.
A proportional-integral adjuster 78 that performs a proportional-integral process on the opening correction command 75 ′ output from the adder 93 and outputs a signal 77 ′; and a signal 7 output from the proportional-integral adjuster 78.
The sum of 7 ′ and the preceding opening command 69 output from the function generator 70 is obtained, and the opening correction command 66 ′ for the reformer combustion air flow rate control valve 61 is transmitted via the automatic / manual switch 79. An adder 80 that outputs to the reformer combustion air flow control valve 61;
A function generator 68 that outputs a rotational speed command 65 of the low-temperature blower 16 based on an output command 63 to the fuel cell 5,
A function generator 95 that outputs a rotation speed correction command 94 of the low-temperature blower 16 based on the opening correction command 66 ′ output from the adder 80, and a rotation speed correction command 94 output from the function generator 95 changes. In this case, a process for limiting the rate of change to a range equal to or less than the set value is performed, and the rotational speed correction command 9 is set.
6 and the rotational speed command 65 output from the function generator 68 when the outlet temperature 82 of the combustion chamber Co of the reformer 3 is equal to or lower than the upper limit 83 as the command 65 ′. While output to the low-temperature blower 16 via the automatic / manual switching device 67, when the outlet temperature 82 of the combustion chamber Co of the reformer 3 exceeds the upper limit value 83, the function generator 95 sends the output through the rate-of-change limiting device 97. And a switch 98 for outputting a rotational speed correction command 96 output as a command 65 ′ to the low-temperature blower 16 via an automatic / manual switch 67.

The function generators 68, 70, 72, 7
Reference numeral 6 denotes a function generator similar to that shown in FIG. 10, and each of the function generators 68, 70, 72, and 76 includes:
Functions such as those shown in FIGS. 3 to 6 are input.
Further, a function as shown in FIG. 7 is input to the function generator 88, and the function is a function of the combustion chamber Co of the reformer 3.
Represents that the opening degree correction command 87 of the reformer combustion air flow control valve 61 is increased or decreased substantially in proportion to the increase or decrease of the outlet temperature deviation 85 of FIG. Also, a function as shown in FIG. 8 is input to the function generator 95, and the function is:
This shows that the rotational speed correction command 94 of the low-temperature blower 16 is increased or decreased substantially in proportion to the increase or decrease of the opening correction command 66 'of the reformer combustion air flow control valve 61.

The reason why the allowable maximum opening 89 of the reformer combustion air flow control valve 61 is set by the signal generator 90 is that the opening of the reformer combustion air flow control valve 61 is set at a certain opening. If the pressure is increased as described above, the pressure difference between the inlet side and the outlet side of the cathode Ca of the fuel cell 5 becomes excessively large, which hinders the operation.
The reason why the rotation speed correction command 96 output from the function generator 95 is limited to a value equal to or less than the set value and the rotation speed correction command 96 is output while the low speed blower 16 is rotating When the pressure is rapidly increased, the pressure difference between the inlet side and the outlet side of the cathode Ca of the fuel cell 5 becomes too large and hinders the operation, so that this is avoided.

Next, the operation of the above embodiment will be described.

During operation of the fuel cell power generator, an output command 63 for the fuel cell 5 is input to the controller 62, and the combustion exhaust gas discharged from the combustion chamber Co of the reformer 3 by the oxygen concentration detector 60. The oxygen concentration 64 contained in the fuel cell 10 is detected, and the outlet temperature 82 of the combustion chamber Co of the reformer 3 is detected by the temperature detector 81, and the oxygen concentration 64 and the outlet temperature 82 are sent to the controller 62 '. Is entered.

When an output command 63 for the fuel cell 5 is input to the function generator 70 of the controller 62 ', the function generator 70 precedes the reformer combustion air flow control valve 61 based on the output command 63. An opening command 69 is obtained, and the preceding opening command 69 is added to the adder 80 and the automatic / manual switch 79.
Is output to the reformer combustion air flow control valve 61, and the opening degree of the reformer combustion air flow control valve 61 is determined by the output command 6.
3 and the output command 63 is input to the function generator 72 of the controller 62 ′ based on the output command 63 based on the output command 63. Oxygen concentration command 7 in flue gas 10
1 is obtained, the oxygen concentration command 71 is output to the subtractor 74, and the oxygen concentration 64 in the combustion exhaust gas 10 detected by the oxygen concentration detector 60 is output to the subtractor 74. The difference between the concentration command 71 and the oxygen concentration 64 is obtained, and an oxygen concentration deviation 73 is output to a function generator 76.
, An opening correction command 75 for the reformer combustion air flow control valve 61 is obtained and output to the adder 93.

When the outlet temperature 82 detected by the temperature detector 81 is input to the subtractor 86 of the controller 62 ', the output temperature of the subtractor 86 is set and output by the signal generator 84. The difference between the outlet temperature 82 of the combustion chamber Co of the porcelain 3 and the upper limit value 83 is determined, and an outlet temperature deviation 85 is output to a function generator 88. The function generator 88 performs reforming based on the outlet temperature deviation 85. A command 87 for correcting the opening of the combustion air flow control valve 61 is output to a proportional-integral adjuster 92 with a limiter. 91 is output to the adder 93. Here, the allowable maximum opening 89 of the reformer combustion air flow rate control valve 61 is input from the signal generator 90 to the limiter-equipped proportional-integral controller 92, and the opening correction command 87 is transmitted to the allowable maximum opening. Degree 89
Is exceeded, the proportional integration process is performed so as not to exceed the allowable maximum opening 89.

In the adder 93, the sum of the opening correction command 75 for the reformer combustion air flow control valve 61 and the signal 91 is obtained, and the opening correction command 75 for the reformer combustion air flow control valve 61 is obtained. Is output to the proportional-integral adjuster 78, the opening degree correction command 75 'is subjected to proportional-integral processing in the proportional-integral adjuster 78, and a signal 77' is output to the adder 80. The sum of the degree command 69 and the signal 77 is obtained, and an opening degree correction command 66 ′ is output to the reformer combustion air flow control valve 61 via the automatic / manual switch 79, and the reformer combustion air flow control is performed. The opening degree of the valve 61 is an output command 63, the oxygen concentration 64 in the flue gas 10 and the reformer 3
Is adjusted based on the outlet temperature 82 of the combustion chamber Co.

On the other hand, an output command 6 for the fuel cell 5
3 is input to the function generator 68 of the controller 62 ', the function generator 68 determines the rotational speed command 65 of the low-temperature blower 16 based on the output command 63, and
When the outlet temperature 82 of the combustion chamber Co is equal to or lower than the upper limit value 83, the rotational speed command 65 is directly sent from the switch 98 to the low temperature blower 1 via the automatic / manual switch 67 as the command 65 '.
The rotation number of the low-temperature blower 16 is controlled based on the output command 63.

The opening correction command 66 'output from the adder 80 via the automatic / manual switch 79 is input to a function generator 95, and the function generator 95 performs the opening correction. A rotation speed correction command 94 of the low-temperature blower 16 is obtained based on the command 66 ′, and is output to the change rate limiter 97.
The rotation rate correction command 96 is output to the switch 98 by performing a process of restricting the rate of change of the rotation speed within a range equal to or less than the set value.

In this state, when the output of the fuel cell 5 is decreased, the outlet temperature 82 of the combustion chamber Co of the reformer 3 is increased to the upper limit value 83.
Is exceeded, a rotation speed correction command 96 output from the function generator 95 via the rate-of-change limiter 97 in place of the rotation speed command 65 is output from the switch 98 as a command 65 'as an automatic / manual switch 67. Is output to the low-temperature blower 16 via
The rotation speed of the low-temperature blower 16 is controlled in accordance with the opening correction command 66 'of the reformer combustion air flow control valve 61.

As a result, when the outlet temperature 82 of the combustion chamber Co of the reformer 3 exceeds the upper limit value 83, the opening of the reformer combustion air flow control valve 61 does not exceed the allowable maximum opening 89. And the rotation speed of the low-temperature blower 16 is increased at a desired rate in accordance with the opening of the reformer combustion air flow control valve 61 and supplied to the combustion chamber Co of the reformer 3. The temperature of the combustion chamber Co is lowered to a required temperature (about 770 ° C.) equal to or lower than the upper limit 83 (about 800 ° C.), and is maintained.

In this way, it is possible to prevent the temperature of the combustion chamber Co of the reformer 3 from rising abnormally when the output of the fuel cell 5 decreases, and to prevent the operation from being stopped.

It should be noted that the fuel cell power generator of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0043]

As described above, according to the fuel cell power generator of the present invention, it is possible to prevent the temperature of the combustion chamber Co of the reformer 3 from rising abnormally when the output of the fuel cell 5 is reduced. In addition, an excellent effect that the operation can be prevented from being stopped can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a controller according to one embodiment of the present invention.

FIG. 3 is a diagram showing functions set in a function generator 68 shown in FIGS. 2 and 10;

FIG. 4 is a diagram showing functions set in a function generator 70 shown in FIGS. 2 and 10;

FIG. 5 is a diagram showing functions set in a function generator 72 shown in FIGS. 2 and 10;

FIG. 6 is a diagram showing functions set in function generator 76 shown in FIGS. 2 and 10;

FIG. 7 is a diagram showing functions set in function generator 88 shown in FIG. 2;

FIG. 8 is a diagram showing a function set in function generator 95 shown in FIG. 2;

FIG. 9 is an overall schematic configuration diagram of a conventional example.

FIG. 10 is a block diagram of a controller in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Reformer 5 Fuel cell 6 Anode exhaust gas 9 Cathode exhaust gas 10 Combustion exhaust gas 16 Low temperature blower 17 Air 21 Turbine compressor 23 Steam 60 Oxygen concentration detector 61 Reformer combustion air flow control valve 63 Output command 64 Oxygen concentration 65 Revolution command 65 'Command 66' Opening correction command 68 Function generator 69 Leading opening command 70 Function generator 71 Oxygen concentration command 72 Function generator 73 Oxygen concentration deviation 74 Subtractor 75 Opening correction command 75 'Opening correction command 76 Function generator 77' Signal 78 Proportional integration controller 80 Adder 81 Temperature detector 82 Outlet temperature 83 Upper limit value 84 Signal generator 85 Outlet temperature deviation 86 Subtractor 87 Opening correction command 88 Function generator 89 Maximum allowable opening 90 Signal generator 91 Signal 92 Proportional integral controller with limiter Third adder 94 rpm correction command 95 function generator 96 the rotational speed correction command 97 change rate limiter 98 switcher An anode Ca cathode Co combustion chamber Re reforming chamber C air compressor T Turbine

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/04 H01M 8/06

Claims (1)

(57) [Claims] 1. A fuel cell (5) having a cathode (Ca) and an anode (An) for generating power, and a fuel gas (1) obtained by adding steam (23) to a source gas (26) is hydrogen A reforming chamber (Re) for supplying an anode (An) of the fuel cell (5) after reforming into an anode gas (2) containing the same, and an anode exhaust gas discharged from the anode (An) of the fuel cell (5) (6) and a cathode exhaust gas (9) discharged from the cathode (Ca) of the fuel cell (5)
A combustion chamber (Co) in which a part of the gas is introduced to perform combustion and generate heat for reforming in the reforming chamber (Re).
And a turbine (T) driven by a cathode exhaust gas (9) discharged from a cathode (Ca) of the fuel cell (5).
A turbine compressor (21) for supplying air (17) from an air compressor (C) driven by the turbine (T) to a cathode (Ca) of a fuel cell (5); The amount of cathode exhaust gas (9) introduced into the combustion chamber (Co) of the reformer (3) is adjusted by adjusting the suction amount by The combustion exhaust gas (10) together with the air (17) from the air compressor (C) of the turbine compressor (21) via the cathode (Ca) of the fuel cell (5) to the reformer (3). Low-temperature blower (1) supplied to the combustion chamber (Co)
6) and a reformer combustion air flow control valve (61) provided on the outlet side of the low temperature blower (16) and controlling the air flow to the combustion chamber (Co) of the reformer (3). A fuel cell power generator comprising: a preceding opening command (69) for a reformer combustion air flow control valve (61) based on an output command (63) to a fuel cell (5);
A function generator (70) for outputting an oxygen concentration command (71) in the combustion exhaust gas (10) based on an output command (63) for the fuel cell (5); An oxygen concentration detector (60) for detecting an oxygen concentration (64) contained in a combustion exhaust gas (10) discharged from a combustion chamber (Co) of the reformer (3); and an output from the function generator (72). The difference between the oxygen concentration command (71) to be performed and the oxygen concentration (64) detected by the oxygen concentration detector (60) is obtained, and the oxygen concentration deviation (73)
Subtractor (74) that outputs the following; and oxygen concentration deviation (73) output from the subtractor (74)
A function generator (76) for outputting an opening degree correction command (75) for the reformer combustion air flow rate control valve (61) based on the output temperature (82) of the combustion chamber (Co) of the reformer (3); )
Temperature detector (81) for detecting the temperature of the combustion chamber (Co) of the reformer (3)
Signal generator (84) for setting and outputting the upper limit value (83)
And an outlet temperature (82) detected by the temperature detector (81).
And an upper limit value (8) output from the signal generator (84).
3) and a subtracter (86) for outputting an outlet temperature deviation (85), and an outlet temperature deviation (85) output from the subtracter (86).
A function generator (88) for outputting an opening correction command (87) for the reformer combustion air flow control valve (61) based on the following formula; and an allowable maximum opening (8) for the reformer combustion air flow control valve (61).
9), a signal generator (90) for setting and outputting, and an opening correction command (87) output from the function generator (88), and an allowable maximum opening (100) output from the signal generator (90). 89) and a proportional-integral controller with limiter (9) that outputs a signal (91) by performing a proportional-integral process so as not to exceed
2), a sum of a signal (91) output from the proportional-integral controller with limiter (92) and an opening correction command (75) output from the function generator (76) is obtained. Adder (93) for outputting an opening correction command (75 ') for the heater combustion air flow control valve (61), and an opening correction command (7) output from the adder (93).
5 ′) is proportionally integrated and a signal (77 ′) is output, and a proportional-integral adjuster (78) is output from the proportional-integral adjuster (78).
7 ′) and the preceding opening command (69) output from the function generator (70) are obtained, and the opening correction command (66 ′) for the reformer combustion air flow control valve (61) is calculated. An adder (80) for outputting to the reformer combustion air flow control valve (61); and a rotational speed command (65) for the low temperature blower (16) based on an output command (63) for the fuel cell (5). A function generator (68) and an opening correction command (6) output from the adder (80).
6 ′), a function generator (95) for outputting a rotation speed correction command (94) for the low-temperature blower (16), and a rotation speed correction command (94) output from the function generator (95) have changed. In such a case, a process for limiting the rate of change to a range equal to or less than the set value is performed, and the rotational speed correction command (96) is issued.
A rate-of-change limiter (97) that outputs a temperature, and an outlet temperature (82) of a combustion chamber (Co) of the reformer (3)
Is less than the upper limit (83), the function generator (68)
The rotation speed command (65) output from the
5 ') to the low-temperature blower (16), while when the outlet temperature (82) of the combustion chamber (Co) of the reformer (3) exceeds the upper limit (83), the function generator (95) The rotation speed correction command (96) output from the controller via the rate-of-change limiter (97) is used as a command (65 ′) as a command (65 ′).
And a switch (98) for outputting to (6).