JP2811277B2 - Temperature control method of gas cooled fuel cell power 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 temperature control system for a gas-cooled fuel cell power generator, which takes into account an increase in the amount of oxidizing gas when the performance of a fuel cell deteriorates.

[0002]

2. Description of the Related Art Fuel cell power generation devices are described in the literature: "Fuel Cell Power Generation System", edited by the Fuel Cell Power Generation System Editing Committee,
As shown in Ohm 1992, fuel gas and oxidizing gas are supplied to generate electricity by an electrochemical reaction.

FIG. 6 is a block diagram showing a configuration of a conventional fuel cell power generator.

As shown in FIG. 1, a fuel reformer 1 reforms hydrocarbons to a fuel cell and supplies the fuel gas as a fuel gas. An oxidizing gas supply device 2 for adding and supplying a gas, a fuel reformer 1, a fuel cell 3 connected to the oxidizing gas supply device 2 by a pipe, an orthogonal transformer 4 connected to a DC output terminal of the fuel cell 3, A circulation blower 10 that circulates from the exhaust side of the fuel cell 3 to the oxidizing gas supply side, and a second that detects the temperature of the mixed gas of the oxidizing gas and the exhaust gas supplied to the fuel cell 3
And a mixed gas temperature controller 12 for controlling the circulation flow rate of the circulation blower 10 so that the mixed gas temperature detected by the second temperature sensor 11 becomes a predetermined value.

[0005] Hydrocarbon supplied from the outside becomes a fuel gas having a high hydrogen concentration by the fuel reformer 1 by a steam reforming method or the like, and is supplied to the fuel electrode 3A of the fuel cell 3. The oxidizing gas, for example, air supplied from the outside is adjusted to a predetermined pressure by an oxidizing gas supply device 2 equipped with a compressor, a preheating device for improving efficiency, etc., and a high temperature exhaust gas from the circulation blower 10 is added to a predetermined temperature. And supplied to the air electrode 3B of the fuel cell 3. The fuel cell 3 generates DC power using the fuel gas and the oxidizing gas. This DC power is supplied to the quadrature converter 4, converted into AC power, and supplied to the load.

Next, basic control of the fuel cell power generator will be described.

The supply flow rates of the fuel gas and the oxidizing gas required for the fuel cell 3 to generate DC power corresponding to the AC power supplied to the load are proportional to the DC output current. Control the supply flow rates of fuel gas and oxidizing gas. Since the electrochemical reaction of the fuel cell 3 has a temperature range suitable for the reaction and is an exothermic reaction, it is necessary to maintain the temperature of the fuel cell 3 in a temperature range suitable for the reaction and to perform cooling to prevent overheating. When the calorific value of the fuel cell 3 is large, the oxidizing gas is used as a coolant so as not to overheat, the oxidizing gas supply temperature is detected, and the exhaust gas circulation amount is controlled to be reduced. When the calorific value is small, the oxidizing gas supply temperature is detected and controlled so as to increase the exhaust gas circulation amount so that the temperature of the fuel cell 3 does not drop below the electrolyte melting point.

[0008]

In the conventional fuel cell power generator, when the performance of the fuel cell is degraded and the DC output is reduced, the DC gas output is secured by increasing the supply amounts of the fuel gas and the oxidizing gas. Since this operation involves an increase in the amount of heat generated by the electrochemical reaction, the ability to cool the fuel cell must be improved. Since the oxidizing gas supply temperature is controlled to be constant by cooling using the oxidizing gas supplied to the fuel cell, the oxidizing gas supply amount must be increased in order to improve the cooling capacity. When the performance of the fuel cell deteriorates, the amount of oxidizing gas required for cooling increases remarkably, and the equipment of the oxidizing gas supply device for cooling must be increased in capacity from the time of construction, and the cost of the fuel cell power generator increases. In addition, the amount of gas passing through the fuel cell at the time of deterioration increases, so that the amount of fuel cell electrolyte scattered increases, thereby causing problems such as shortening the service life.

An object of the present invention is to prevent an increase in the supply flow rate of oxidizing gas as a coolant when the fuel cell is operated with a reduced activity and an increased amount of electrochemical reaction.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell for generating electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, a fuel gas supply means for supplying the fuel gas to the fuel cell, and a cooling system for the fuel cell. Oxidizing gas supply means for supplying the oxidizing gas used as a part of the material, exhaust gas circulating means for supplying exhaust gas from the fuel cell to an outlet side of the oxidizing gas supply means, and A gas-cooled fuel cell power generator comprising: a mixed gas temperature control means for detecting a mixed gas temperature of the oxidizing gas and the exhaust gas and controlling a supply capacity of the exhaust gas circulating means, provided at an outlet of the oxidizing gas supply means. Oxidizing gas cooling means for cooling the oxidizing gas,
A fuel cell reaction amount detecting means for detecting a reaction amount of the fuel cell; and a reaction amount of the fuel cell detected by the fuel cell reaction amount detecting means for receiving a restriction of the fuel cell electrolyte melting point.
This is attained by providing an oxidizing gas temperature control means for outputting a control amount to the oxidizing gas cooling means in accordance with a temperature control set value which is not changed.

The object is to provide a fuel cell for generating electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, fuel gas supply means for supplying the fuel gas to the fuel cell, and use as a part of a coolant for the fuel cell. An oxidizing gas supply means for supplying the oxidizing gas, an exhaust gas circulating means for supplying exhaust gas from the fuel cell to an outlet of the oxidizing gas supply means, and a mixing of the oxidizing gas and exhaust gas supplied to the fuel cell. A gas-cooled fuel cell power generator comprising a mixed gas temperature control means for detecting a gas temperature and controlling a supply capacity of the exhaust gas circulation means, provided at an outlet of the oxidizing gas supply means for cooling the oxidizing gas. Oxidizing gas cooling means, oxidizing gas temperature detecting means for detecting the temperature of the oxidizing gas at the outlet of the oxidizing gas cooling means, and inputting the temperature detected by the temperature detecting means to the oxidizing gas cooling means Oxidizing gas temperature control means for outputting, fuel cell reaction amount detecting means for detecting the reaction amount of the fuel cell, and oxidizing gas temperature control by inputting the reaction amount of the fuel cell detected by the fuel cell reaction amount detecting means. Before the means
This is achieved by providing oxidizing gas temperature setting means for setting a temperature control set value which is not restricted by the fuel cell electrolyte melting point .

The object of the present invention is to provide a fuel cell for generating electric power by an electrochemical reaction between a fuel gas and an oxidizing gas, a fuel gas supply means for supplying the fuel gas to the fuel cell, and a cooling material for the fuel cell. An oxidizing gas supply means for supplying the oxidizing gas, an exhaust gas circulating means for supplying exhaust gas from the fuel cell to an outlet of the oxidizing gas supply means, and a mixing of the oxidizing gas and exhaust gas supplied to the fuel cell. A mixed gas temperature control means for detecting gas temperature and controlling the supply capacity of the exhaust gas circulation means, wherein the cooling medium or a low-temperature device provided at an outlet of the oxidizing gas supply means. A heat exchanger for exchanging heat with the internal fluid, a bypass line for bypassing the heat exchanger, an oxidizing gas cooling means having a control valve disposed on the bypass line, and a reaction amount of the fuel cell are detected. To the fuel cell reaction amount detecting means, the fuel cell reaction amount detecting means is not limited by the type of reaction the amount of the fuel cell detected the fuel cell electrolyte melting temperature
This is achieved by providing oxidizing gas temperature control means for outputting a control amount to a control valve of the oxidizing gas cooling means according to the degree control set value .

[0013] The object of the present invention is to provide a fuel cell for generating electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, a fuel gas supply means for supplying the fuel gas to the fuel cell, and a part of a coolant for the fuel cell. An oxidizing gas supply means for supplying the oxidizing gas, an exhaust gas circulating means for supplying exhaust gas from the fuel cell to an outlet of the oxidizing gas supply means, and a mixing of the oxidizing gas and exhaust gas supplied to the fuel cell. A mixed gas temperature control means for detecting gas temperature and controlling the supply capacity of the exhaust gas circulation means, wherein the cooling medium or a low-temperature device provided at an outlet of the oxidizing gas supply means. Oxidizing gas cooling means having a heat exchanger for exchanging heat with the internal fluid, a bypass line for bypassing the heat exchanger, and a control valve disposed on the bypass line, and an outlet of the oxidizing gas cooling means Oxidizing gas temperature detecting means for detecting the oxidizing gas temperature, oxidizing gas temperature controlling means for inputting the temperature detected by the temperature detecting means and outputting a control amount to a control valve of the oxidizing gas cooling means, and a reaction of the fuel cell Fuel cell reaction amount detection means for detecting the amount of fuel, and the reaction amount of the fuel cell detected by the fuel cell reaction amount detection means is input, and the oxidizing gas temperature control means is not limited by the fuel cell electrolyte melting point. This is achieved by providing oxidizing gas temperature setting means for setting a temperature control set value.

[0014]

[0015]

[0016]

[0017]

When the performance of the fuel cell is degraded, the fuel cell is operated with an increased amount of reaction in order to obtain a rated output, but the calorific value also increases. According to the above configuration, the increase in the reaction amount of the fuel cell is detected by the fuel cell reaction amount detection means, and the oxidizing gas temperature control means controls the oxidizing gas cooling means to increase the cooling amount by increasing the reaction amount detection value. As a result, the temperature of the oxidizing gas decreases, and the fuel cell is cooled without increasing the flow rate of the oxidizing gas, thereby preventing an increase in the oxidizing gas supply flow rate. The oxidizing gas supplied to the fuel cell and the exhaust
If the gas mixture temperature is higher than the melting point of the electrolyte,
Temperature can be lowered below the melting point of the electrolyte.
Wide range to cope with increase in reaction volume due to deterioration of battery performance
It becomes. Further, since the amount of gas passing through the fuel cell does not increase, the scattering of the electrolyte is prevented, and the life of the fuel cell can be extended.

The oxidizing gas temperature control means for controlling the temperature of the oxidizing gas at the outlet of the oxidizing gas cooling means can be controlled stably by forming a cascade control loop for setting the oxidizing gas temperature control means based on the reaction amount of the fuel cell.

Further, when the performance of the fuel cell deteriorates, the DC output voltage decreases. When the reaction amount is increased to secure the rated output of the fuel cell, the DC output current increases, so that the reaction amount can be detected by detecting the DC output current.

Since the amount of heat generated by the increase in the amount of reaction increases, the body temperature of the fuel cell increases, and the amount of reaction can be detected by detecting the body temperature.

An increase in the reaction amount is accompanied by an increase in the oxidizing gas and the fuel gas and an increase in the temperature of the main body. The reaction amount can be detected by calculating and calculating the exhaust heat amount.

Next, when the control valve disposed on the bypass line of the heat exchanger of the oxidizing gas cooling means is controlled by the oxidizing gas temperature control means, the ratio of the oxidizing gas divided into the heat exchanger and the bypass line changes. The temperature of the gas can be controlled.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

First, the configuration of this embodiment will be described.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

As shown in this figure, this embodiment comprises a fuel reformer 1 for reforming hydrocarbons such as methane to a fuel cell and supplying it as a fuel gas, and increasing the pressure of an oxidizing gas which also serves as a fuel for the fuel cell. An oxidizing gas supply device 2 for adding and supplying carbon dioxide from the reforming device 1, a fuel cell 3 connected to the fuel reforming device 1 and the oxidizing gas supply device 2, and a DC output terminal of the fuel cell 3 Orthogonal transformation device 4, oxidizing gas supply device 2
An oxidizing gas cooling device 5 provided at the outlet of
First detecting the temperature of the oxidizing gas at the outlet of the oxidizing gas cooling device 5
Temperature sensor 6, an oxidizing gas temperature controller 7 for inputting a detection signal of the first temperature sensor 6 and outputting a control signal to the oxidizing gas cooling device 5, a DC current sensor for detecting a reaction amount of the fuel cell as a DC output current 8. An oxidizing gas temperature setter 9 for inputting a DC current detected by the DC current sensor 8 and setting a temperature control set value of the oxidizing gas temperature controller 7, circulating exhaust gas from the exhaust side of the fuel cell 3 to the oxidizing gas supply side. Circulation blower 10 (not shown), second temperature sensor 1 (not shown) for detecting the temperature of a mixed gas of oxidizing gas and exhaust gas supplied to fuel cell 3
First, a mixed gas temperature controller 12 (not shown) that controls the circulation flow rate of the circulation blower 10 so that the mixed gas temperature detected by the second temperature sensor 11 becomes a predetermined value.

FIG. 2 is an explanatory diagram illustrating the configuration of the oxidizing gas cooling device of FIG.

As shown in the figure, the oxidizing gas cooling device includes a heat exchanger 13 for exchanging heat with the oxidizing gas from the oxidizing gas supply device 2 and cooling water or a low-temperature process fluid, and a bypass line 14 for bypassing the heat exchanger 13. , Bypass line 14
And a control valve 15 which is operated by a control signal from the oxidizing gas temperature controller 7, and a valve 16 which is disposed on the oxidizing gas inlet side of the heat exchanger 13.

When it is not necessary to cool the oxidizing gas without deteriorating the performance of the fuel cell 3, the valve 16 is fully closed and the control valve 15 is fully opened. When the performance of the fuel cell 3 is deteriorated and the oxidizing gas is cooled, the valve 16 is opened and the opening of the control valve 15 is changed by the control signal from the oxidizing gas temperature controller 7 to control the oxidizing gas temperature.

Next, the operation of this embodiment will be described.

The control characteristic of the output signal of the oxidizing gas temperature setting device 9 is determined in advance so that the temperature setting value of the oxidizing gas temperature controller 7 becomes relatively small as the detection signal of the DC current sensor 8 increases.

FIG. 3 is a table for explaining the temperature setting of the oxidizing gas temperature controller of FIG.

As shown in the figure, the temperature setting of the oxidizing gas temperature controller 7 is lowered as the reaction amount increases due to the deterioration of the performance of the fuel cell. However, it is natural that the temperature must be kept higher than the melting point of the electrolyte. .

Next, another embodiment of the present invention will be described.

FIG. 4 is a block diagram showing the configuration of another embodiment of the present invention.

In this embodiment, as shown in this figure, a single or a plurality of third temperature sensors 17 for detecting the temperature of the main body of the fuel cell are used in place of the DC current sensor 8 of FIG. By detecting the temperature of the main body, an increase in the reaction amount of the fuel cell can be detected. Other configurations are the same as those in FIG.

FIG. 5 is a block diagram showing the configuration of another embodiment of the present invention.

In this embodiment, as shown in this figure, a fourth embodiment for detecting the exhaust temperature of the fuel cell in place of the DC current sensor 8 of FIG.
Temperature sensor 18, fuel flow meter 1 for detecting fuel flow rate
9. The flow rate of both the oxidizing gas and the fuel gas or any one of them is detected by using the oxidizing gas flow meter 20 for detecting the flow rate of the oxidizing gas. The amount of exhaust heat is calculated from the detected flow rates of both the oxidizing gas and the fuel gas and the exhaust gas temperature to obtain the reaction amount. Alternatively, one of the oxidizing gas and the fuel gas can be detected and the other can be determined by a reaction correlation.
Other configurations are the same as those in FIG.

[0039]

According to the present invention, when the performance of a fuel cell is degraded and the calorific value increases due to an increase in the amount of electrochemical reaction, control is performed to detect the amount of reaction and decrease the oxidizing gas supply temperature. In addition, the fuel cell can be cooled without increasing the flow rate of the oxidizing gas, thereby preventing an increase in the flow rate of the oxidizing gas supply. Then, the temperature of the mixed gas supplied to the fuel cell is
If the temperature is higher than the melting point, the temperature of the oxidizing gas should be lower than the electrolyte melting point.
Range that can be reduced to accommodate the increase in reaction volume.
The area becomes wider. Further, since the amount of gas passing through the fuel cell does not increase, the scattering of the electrolyte is prevented, and the life of the fuel cell can be extended.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of an oxidizing gas cooling device of FIG.

FIG. 3 is a table illustrating temperature settings of the oxidizing gas temperature controller of FIG. 1;

FIG. 4 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional fuel cell power generator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel reforming device 2 oxidizing gas supply device 3 fuel cell 3A fuel electrode 3B air electrode 4 orthogonal transformation device 5 oxidizing gas cooling device 6 first temperature sensor 7 oxidizing gas temperature controller 8 DC current sensor 9 oxidizing gas temperature setting device Reference Signs List 10 circulation blower 11 second temperature sensor 12 mixed gas temperature controller 13 heat exchanger 14 bypass line 15 control valve 16 valve 17 third temperature sensor 18 fourth temperature sensor 19 fuel flow meter 20 oxidizing gas flow meter

Continuation of the front page (56) References JP-A-62-252075 (JP, A) JP-A-58-164165 (JP, A) JP-A-4-206159 (JP, A) JP-B-48-40369 (JP) , B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 8/00-8/24

Claims (4)

(57) [Claims] 1. A fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidizing gas, a fuel gas supply unit that supplies the fuel gas to the fuel cell, and a fuel cell that is used as a part of a coolant of the fuel cell. An oxidizing gas supply unit that supplies an oxidizing gas; an exhaust gas circulation unit that supplies exhaust gas from the fuel cell to an outlet of the oxidizing gas supply device; and a mixed gas temperature of the oxidizing gas and the exhaust gas supplied to the fuel cell. And a mixed gas temperature control means for controlling the supply capacity of the exhaust gas circulating means. The oxidizing gas provided at an outlet of the oxidizing gas supply means for cooling the oxidizing gas. and cooling means, and the fuel cell reaction amount detecting means for detecting the reaction of the fuel cell, the fuel enter the reaction amount of the fuel cell is the fuel cell reaction detecting means detects
An oxidizing gas temperature control means for outputting a control amount to the oxidizing gas cooling means according to a temperature control set value which is not restricted by a battery electrolyte melting point . Temperature control method. 2. A fuel cell for generating power by an electrochemical reaction between a fuel gas and an oxidizing gas, fuel gas supply means for supplying the fuel gas to the fuel cell, and a fuel cell used as a part of a coolant for the fuel cell. An oxidizing gas supply unit that supplies an oxidizing gas; an exhaust gas circulation unit that supplies exhaust gas from the fuel cell to an outlet of the oxidizing gas supply device; and a mixed gas temperature of the oxidizing gas and the exhaust gas supplied to the fuel cell. And a mixed gas temperature control means for controlling the supply capacity of the exhaust gas circulating means. The oxidizing gas provided at an outlet of the oxidizing gas supply means for cooling the oxidizing gas. A cooling unit, an oxidizing gas temperature detecting unit for detecting an outlet oxidizing gas temperature of the oxidizing gas cooling unit, and inputting the temperature detected by the temperature detecting unit and outputting a control amount to the oxidizing gas cooling unit Of the gas temperature control means, and the fuel cell reaction amount detecting means for detecting the reaction of the fuel cell, enter the reaction amount of the fuel cell is the fuel cell reaction detecting means detects the oxidizing gas temperature control means The fuel cell power
A temperature control method for a gas-cooled fuel cell power generator, comprising: an oxidizing gas temperature setting means for setting a temperature control set value which is not restricted by a decomposition melting point . 3. A fuel cell for generating power by an electrochemical reaction between a fuel gas and an oxidizing gas, fuel gas supply means for supplying the fuel gas to the fuel cell, and a fuel cell used as a part of a coolant for the fuel cell. An oxidizing gas supply unit that supplies an oxidizing gas; an exhaust gas circulation unit that supplies exhaust gas from the fuel cell to an outlet of the oxidizing gas supply device; and a mixed gas temperature of the oxidizing gas and the exhaust gas supplied to the fuel cell. And a mixed gas temperature control means for controlling the supply capacity of the exhaust gas circulation means, and a cooling medium or a low-temperature internal fluid provided at an outlet of the oxidizing gas supply means. Oxidizing gas cooling means having a heat exchanger for exchanging heat with a heat exchanger, a bypass line for bypassing the heat exchanger, and a control valve disposed on the bypass line, and a fuel for detecting a reaction amount of the fuel cell Pond reaction amount detecting means and, the fuel cell reaction volume not detecting means inputs the reaction amount of the fuel cell detected restricted the fuel cell electrolyte melting point temperature control set
An oxidizing gas temperature control means for outputting a control amount to a control valve of the oxidizing gas cooling means according to a constant value . 4. A fuel cell for generating power by an electrochemical reaction between a fuel gas and an oxidizing gas, fuel gas supply means for supplying the fuel gas to the fuel cell, and a fuel cell used as a part of a coolant for the fuel cell. An oxidizing gas supply unit that supplies an oxidizing gas; an exhaust gas circulation unit that supplies exhaust gas from the fuel cell to an outlet of the oxidizing gas supply device; and a mixed gas temperature of the oxidizing gas and the exhaust gas supplied to the fuel cell. And a mixed gas temperature control means for controlling the supply capacity of the exhaust gas circulation means, and a cooling medium or a low-temperature internal fluid provided at an outlet of the oxidizing gas supply means. Oxidizing gas cooling means having a heat exchanger for exchanging heat with a heat exchanger, a bypass line bypassing the heat exchanger, and a control valve disposed in the bypass line, and an oxidizing gas temperature at the outlet of the oxidizing gas cooling means. Oxidizing gas temperature detecting means for detecting the temperature, oxidizing gas temperature controlling means for inputting the temperature detected by the temperature detecting means and outputting a control amount to a control valve of the oxidizing gas cooling means, and detecting a reaction amount of the fuel cell A fuel cell reaction amount detecting means for inputting a reaction amount of the fuel cell detected by the fuel cell reaction amount detecting means, and setting a temperature control set value of the oxidizing gas temperature control means which is not restricted by the fuel cell electrolyte melting point. A temperature control method for a gas-cooled fuel cell power generator, comprising: an oxidizing gas temperature setting means for setting.