JPH0676847A - Starting method for fuel cell and device thereof - Google Patents

Abstract

PURPOSE:To feed the reformed gas to a heated fuel cell at good timing so that no harmful effect is given to the electrode catalyst of a fuel cell by the carbon monoxide concentration in the reformed gas from a heated carbon monoxide converter when a fuel cell power generating device is started. CONSTITUTION:The relation between the carbon monoxide concentration in the reformed gas detected by a concentration detector 30 and the temperature of a fuel cell main body 5 detected by a temperature detector 6 is stored in a memory section 31, and the relation between the carbon monoxide concentration giving no harmful effect to an electrode catalyst and the temperature of the fuel cell main body 5 is read out. When no effect is given, an electric valve 13 is closed and electric valves 11, 16, 18 are opened by a controller 32, and the reformed gas and air are fed to the fuel cell main body 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a fuel cell having a phosphoric acid electrolyte incorporated in a fuel cell power generator and a starting apparatus for the same.

[0002]

2. Description of the Related Art A fuel reforming apparatus for reforming a hydrocarbon-based raw fuel into a gas rich in hydrogen, and a fuel cell having a phosphoric acid electrolyte for generating electricity using the reformed gas reformed by the reforming apparatus as fuel. There is known a phosphoric acid fuel cell power generation device including and. By the way, at the time of starting the phosphoric acid fuel cell power generator, the temperature of the fuel reformer is raised and the raw fuel is allowed to flow through the reformer to raise the temperature of the reformed gas to a temperature suitable for causing the cell reaction. The fuel cell is supplied to the fuel cell, and the fuel cell is caused to generate electricity by the air supplied separately.

The prior art will be described below with reference to the drawings. FIG. 3 is a system diagram of a conventional phosphoric acid fuel cell power generator. In FIG. 3, the fuel reformer comprises a desulfurizer 1, a reformer 2, and a carbon monoxide shift converter 3. The desulfurizer 1 desulfurizes the sulfur content of the hydrocarbon-based raw fuel under a desulfurization catalyst. The reformer 2 heats the reforming tube filled with the reforming catalyst by the combustion gas generated by the combustion in the burner 4 to cause the desulfurized raw fuel from the desulfurizer 1 flowing through the reforming tube to flow under the reforming catalyst. Steam reforms to hydrogen-rich gas. The carbon monoxide shift converter 3 shifts carbon monoxide contained in the steam reformed gas from the reformer 2 into carbon dioxide to generate a reformed gas having a reduced carbon monoxide concentration.

The fuel cell main body 5 is in contact with the matrix impregnated with and carrying the phosphoric acid electrolyte, the fuel electrode and the air electrode sandwiching this matrix, and each of these electrodes, and reforming as a reaction gas supplied to each electrode. It is composed of a cell stack in which cells made of a base material having passages through which gas and air respectively flow are laminated. A temperature detector 6 detects the temperature of the fuel cell body 5.

The raw fuel supply system 7 supplies the raw fuel from the raw fuel supply source to the desulfurizer 1. Desulfurization raw fuel supply system 8 is desulfurizer 1
The raw fuel desulfurized in 1 is supplied to the reforming pipe of the reformer 2.
The steam reformed gas supply system 9 supplies the gas reformed by the reformer 2 to the carbon monoxide shift converter 3. The reformed gas supply system 10 includes a motor-operated valve 11, and supplies the reformed gas having a low concentration of carbon monoxide in the carbon monoxide shift converter 3 to the fuel cell body 5.

The reformed gas bypass system 12 is provided with a motor-operated valve 13, and supplies the reformed gas delivered from the carbon monoxide shift converter 3 to the burner 4 of the reformer 2 by bypassing the fuel cell body 5. The off-gas supply system 15 is equipped with a motor-operated valve 16 and is provided so as to join the reformed gas bypass system 12 from the fuel electrode. When the fuel cell main body 5 generates power, the off-gas supply system 15 is discharged from the fuel electrode including hydrogen that does not contribute to the cell reaction. The off gas is supplied to the burner 4 of the reformer 2.

The air supply system 17 is provided with an electric valve 18 and supplies air to the air electrode of the fuel cell body 5. Air exhaust system 19
Discharges the exhaust air discharged from the air electrode to the outside. The nitrogen supply system 21 merges with the raw fuel supply system 7, while the nitrogen discharge system 22 is provided so as to branch from the reformed gas supply system 10, and is used to remove nitrogen from the desulfurizer 1, the reformer 2, and the carbon monoxide shift converter 3 Flow to. In addition, 23 and 24 are valves.

The battery nitrogen supply system 25 branches to join the reformed gas supply system 10 and the air supply system 17, while the battery nitrogen discharge system 26 is provided to branch from the off-gas discharge system 15 to remove nitrogen. The reformed gas and air of the fuel cell body 5 are made to flow. In addition, 27, 28, and 29 are valves. With this configuration, when the fuel cell power generator is started, the valve 2
Opening valves 3 and 24, the combustible gas in the desulfurizer 1, the reformer tubes of the reformer 2 and the carbon monoxide shift converter 3 is gas-purged with nitrogen, and when the gas purging is completed, the valves 23 and 24 are closed. The desulfurizer 1 is operated by an electric heater, the reforming pipe of the reformer 2 is operated by combustion gas from the burner 4, and the carbon monoxide shift converter 3 is driven by an electric heater to desulfurize catalyst, reforming catalyst, carbon monoxide shift catalyst. And the raw fuel is caused to flow through the fuel reforming device for reforming. That is, the raw fuel is sent to the desulfurizer 1 via the raw fuel supply system 7 to desulfurize the sulfur content contained in the raw fuel. Then, the desulfurized raw fuel is sent to the reformer 2 to steam-reform the raw fuel and reform it into a gas rich in hydrogen. Next, this gas is sent to the carbon monoxide shift converter 3 to shift the carbon monoxide contained in this gas to reduce the carbon monoxide concentration.

The reformed gas whose carbon monoxide concentration has been reduced in this way is supplied to the reformed gas bypass system 12 while the motor-operated valves 11 and 16 are closed and the motor-operated valve 13 is opened to supply the reformed gas to the fuel cell body 5. After that, it is supplied to the burner 4 of the reformer 2 and used as a fuel. On the other hand, in the fuel cell main body 5, the valves 27,
Opening 28 and 29, nitrogen is passed through the nitrogen supply system 25 to the passage of the reformed gas and air of the fuel cell main body 5 to purge hydrogen and oxygen, and to cool the fuel cell main body 5 at high temperature. Water raises the temperature of the fuel cell body 5 to a temperature suitable for causing a cell reaction. In addition, the valves 27 and 2 are used after the gas purging is completed.
8, 29 are closed.

The temperature of the fuel cell body 5 is detected by the temperature detector 6
When the detected temperature reaches a temperature suitable for the cell reaction, the electrically operated valve 13 is closed and the electrically operated valves 11 and 16 are opened to supply the reformed gas from the carbon monoxide shift converter 3 to the fuel cell main body 5. At the same time, the electric valve 18 is opened to supply air to the fuel cell body 5 through the air supply system 17. The supplied reformed gas and air cause the fuel cell main body 5 to undergo a cell reaction to generate electricity.

[0011]

As described above, when the fuel cell power generator is started, the temperature of the fuel reformer including the desulfurizer 1, the reformer 2 and the carbon monoxide shifter 3 is raised, and The fuel is charged and reformed, and the temperature of the fuel cell main body 5 is simultaneously raised. By the way, the conventional fuel cell body 5
The gas supply timing at which the reformed gas, which is a reaction gas, and air are supplied to generate power is determined only by the temperature of the fuel cell body 5.

However, in the starting method as described above, the temperature rising rate of the fuel reformer and the temperature rising rate of the fuel cell body 5 generally do not match, so that the temperature of the fuel cell body 5 is sufficiently raised. Despite this, there is a case where the temperature of the fuel reformer, especially the carbon monoxide transformer, is not raised. Further, depending on the operation history of the fuel cell power generator, the temperature rise does not always start in the same starting state.

In the above case, unless the temperature of the carbon monoxide shift converter 3 is raised to a predetermined temperature, the reaction for converting carbon monoxide into carbon dioxide does not proceed, so that a high concentration of carbon monoxide is generated. The reformed gas containing the gas is supplied to the fuel cell body 5 to poison the electrode catalyst of the fuel cell body 5. Further, when the shift conversion catalyst of the carbon monoxide shift converter 3 deteriorates, the carbon monoxide concentration does not sufficiently decrease even at the same temperature in the carbon monoxide shift converter,
The electrode catalyst is poisoned as described above.

When the carbon monoxide shift converter 3 and the fuel cell main body 5 are sufficiently heated and then the reformed gas and air from the carbon monoxide shift converter 3 are supplied to the fuel cell main body 5, power generation starts. There is a problem that it takes a long time. An object of the present invention is to raise the temperature of a fuel reforming device at the time of starting a fuel cell power generation device to generate a reformed gas from a carbon monoxide shift converter, the carbon monoxide concentration of which is contained in an electrode catalyst of a fuel cell. (EN) A fuel cell start-up method and device capable of supplying power to a fuel cell whose temperature is raised in a timely manner to start power generation at a concentration that does not give harmful poisoning to the fuel cell.

[0015]

In order to solve the above-mentioned problems, according to the present invention, hydrogen supplied from a carbon monoxide converter for converting carbon monoxide contained in a gas obtained by steam reforming a raw fuel is used. In a method for starting a fuel cell having a phosphoric acid electrolyte that generates electricity with air supplied together with a rich reformed gas, at the time of start-up, the carbon monoxide shifter and the fuel cell body are heated and heated, and the carbon monoxide shifter is also heated. The carbon monoxide concentration in the reformed gas sent from the fuel cell and the temperature of the fuel cell body were measured, and the carbon monoxide concentration reached a concentration that did not cause harmful poisoning of the electrode catalyst with respect to the temperature of the fuel cell body. When I did
The reformed gas and air are supplied to the fuel cell body.

Further, as a device when the above-mentioned starting method is adopted, the raw fuel is supplied together with a hydrogen-rich reformed gas supplied from a carbon monoxide shifter for transforming carbon monoxide contained in the steam reformed gas. And a concentration detector for detecting the concentration of carbon monoxide contained in the reformed gas sent from the carbon monoxide shift converter, in a fuel cell starter for starting a fuel cell having a phosphoric acid electrolyte that generates electricity with the generated air. A temperature detector for detecting the temperature of the fuel cell main body, a memory unit for storing the relationship between the temperature of the fuel cell main body and the carbon monoxide concentration which does not cause harmful poisoning to the electrode catalyst with respect to this temperature, The signals of carbon monoxide concentration and temperature detected by the detector and the temperature detector are input, and based on the relationship read from the memory unit, the supply system that supplies the reformed gas and air to the fuel cell is installed. The resulting valve is intended to comprise a control unit to open.

[0017]

[Function] Hydrocarbon-based raw fuel is desulfurized by a desulfurizer, steam-reformed by a reformer, and then carbon monoxide contained in the reformed gas is converted by a carbon monoxide shift converter to form carbon monoxide. The reformed gas with low concentration is supplied to the fuel cell. The fuel cell generates electricity by using this reformed gas and air supplied separately.

By the way, at the time of start-up before the start of power generation, the temperature of the carbon monoxide shift converter is raised and the steam-reformed gas is introduced to transform the carbon monoxide, and at the same time, the temperature of the fuel cell main body is raised. At this time, the concentration of carbon monoxide in the reformed gas in which carbon monoxide was transformed from the carbon monoxide transformer and the temperature of the fuel cell body were measured, and the carbon monoxide concentration was measured with respect to the temperature of the fuel cell body. When the concentration reaches a level that does not give harmful poisoning to the electrode catalyst, reforming gas and air are supplied to the fuel cell body to start power generation.

In the starting device adopting the above-mentioned starting method, the temperature of the carbon monoxide shift converter is raised so that the concentration of carbon monoxide in the reformed gas which has been subjected to the shift of carbon monoxide is detected by the concentration detector. To detect. On the other hand, the temperature detector detects the temperature of the main body of the fuel cell. And the relationship between the temperature of the fuel cell main body corresponding to the concentration of carbon monoxide read from the memory section the relationship between the detected concentration and the detected temperature by the control section and the carbon monoxide concentration that does not give harmful poisoning to the electrode catalyst, In comparison, when the carbon monoxide concentration is the temperature of the fuel cell main body that does not cause harmful poisoning to the electrode catalyst, the valve of the supply system that supplies the reformed gas and air is opened and the reformed gas is supplied to the fuel cell main body. And air are supplied to start power generation.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a fuel cell power generator when a method of starting a fuel cell according to an embodiment of the present invention is adopted. In FIG. 1, the same parts as those in the conventional example of FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. 1 is different from the conventional example as follows.

The concentration detector 30 is a reformed gas bypass system 12
And detects the concentration of carbon monoxide contained in the reformed gas delivered from the carbon monoxide shift converter 3. Memory unit 31
Stores the relationship between the temperature of the fuel cell body 5 and the concentration of carbon monoxide contained in the reformed gas that does not cause harmful poisoning of the electrode catalyst of the fuel cell body with respect to this temperature. FIG. 2 illustrates this relationship, in which the horizontal axis represents the temperature (° C.) of the fuel cell body 5 and the vertical axis represents the carbon monoxide concentration (%), and the curve X represents the temperature of the fuel cell body 5. The concentration of carbon monoxide that does not cause harmful poisoning of the electrode catalyst is shown. From the figure, it is understood that poisoning by carbon monoxide of the electrode catalyst is less likely to occur as the temperature of the fuel cell body 5 increases. Here, the lower portion of the curve X (hatched portion) is the region where the reformed gas can be supplied to the fuel cell,
That is, it is a power generation possible region.

The control unit 32 receives a signal of the temperature of the fuel cell body 5 detected by the temperature detector 6 and a signal of the carbon monoxide concentration detected by the concentration detector 30, and inputs these temperature and monoxide. When the carbon concentration reaches the relationship between the temperature of the fuel cell body and the carbon monoxide concentration stored in the memory unit 31, that is, when the curve X in FIG. 2 is reached, the reformed gas from the carbon monoxide shift converter 3 is discharged. The motor-operated valve 13 is closed, the motor-operated valves 11 and 16 are opened so that the fuel cell body 5 can be supplied, and the motor-operated valve 18 is opened so that air can be supplied to the fuel cell body 5.

With such a configuration, when the fuel cell power generator is started, the carbon monoxide shift converter 3 is heated and the carbon monoxide is transformed as described above. Along with this, the fuel cell body 5 is also heated. As an example of this case, in FIG. 2, the carbon monoxide concentration in the reformed gas sent from the carbon monoxide shift converter 3 is detected by the concentration detector 30 and the fuel cell is detected by the temperature detector 6. A change with time of the temperature of the main body 5 is shown by a line 34.

In line 34, the relationship between the concentration of carbon monoxide and the temperature of the fuel cell body 5 with time is A → B → C → D →
Change to E. Here, since points A, B, and C are above the curve X, the reformed gas cannot be supplied to the fuel cell body 5, and points D and E are below the curve X. Of the fuel cell body 5, that is, power generation is possible.

If the time from when the fuel cell power generator is stopped to when it is restarted is short, the carbon monoxide transformer 3 is not sufficiently cooled, and as shown by the line 35 in FIG. It is possible to supply the reformed gas to the fuel cell main body 5 at a temperature (point F) where the carbon monoxide concentration is lowered earlier than the temperature rise of the fuel cell main body 5 and the temperature of the fuel cell main body is lower. In the example shown by the line 36 in FIG. 2, the temperature of the fuel cell body is higher (point G) even if the carbon monoxide concentration is high.
Thus, the reformed gas can be supplied to the fuel cell body 5.

When the shift catalyst of the carbon monoxide shift converter deteriorates with the lapse of the operating time of the fuel cell power generator, the carbon monoxide concentration increases even if the heating rate of the carbon monoxide shift converter is the same. Also in this case, the temperature of the fuel cell main body 5 that can supply the reformed gas to the fuel cell main body 5 is the temperature according to the curve X in FIG. By the way, if the temperature of the fuel cell main body 5 becomes 150 ° C. or higher as in the conventional case, the reforming gas and the air are supplied to the fuel cell main body to start power generation, and the line 34 is generated. In the case of the history like this, there is no problem, but in the case of the history like the line 35, the time until the power generation becomes long regardless of whether the power generation can be started at a lower temperature of the fuel cell main body. Further, in the case of the history as shown by the line 36, there is a disadvantage that power generation is started even if the carbon monoxide concentration is high.

However, according to the present invention, the relationship between the concentration of carbon monoxide in the reformed gas detected by the concentration detector 30 and the temperature detector 6 and the temperature of the fuel cell body is read from the memory unit 31. If the relationship between the temperature of the main body and the concentration of carbon monoxide, that is, the power generation possible region of the curve X shown in FIG.
6 can be opened to supply reformed gas, and the motor-operated valve 18 can be opened to supply air to the fuel cell main body 5 to generate electric power.
That is, for example, in the history such as the line 34, the reformed gas and air are supplied to the fuel cell at point D to generate power. After power generation, the fuel cell main body 5 and the carbon monoxide shift converter 3 are raised and maintained at the normal operating temperature (point E). Further, in the history like the line 35, at the point F, the reformed gas and air are supplied to the fuel cell main body 5 as described above to generate power. In the history like the line 36, power is generated at point G as described above. Therefore, in any of the above cases, the reformed gas is supplied to the fuel cell body 5 whose temperature is raised in a timely manner according to the concentration of carbon monoxide contained in the reformed gas to generate electric power, and does not give harmful poisoning to the electrode catalyst. .

Although air is supplied to the air electrode of the fuel cell in this embodiment, oxygen may be supplied.

[0029]

As is apparent from the above description, according to the present invention, the carbon monoxide transformer can be used in various starting states of the fuel cell power generator by the starting method and the configuration of the apparatus. Power generation at the temperature of the main body of the fuel cell that does not cause harmful poisoning to the electrode catalyst of the fuel cell according to the concentration of carbon monoxide in the reformed gas sent from the carbon monoxide shifter even if the shift catalyst of Therefore, the power generation of the fuel cell can be started in the shortest time with less adverse effect on the electrode catalyst.

[Brief description of drawings]

FIG. 1 is a system diagram of a phosphoric acid fuel cell power generator including a fuel cell starter according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the concentration of carbon monoxide in the reformed gas and the temperature of the fuel cell body, which enables the reformed gas to be supplied from the carbon monoxide shift converter to the fuel cell in FIG.

FIG. 3 is a system diagram of a conventional phosphoric acid fuel cell power generator.

[Explanation of symbols]

 1 desulfurizer 2 reformer 3 carbon monoxide shifter 5 fuel cell body 6 temperature detector 10 reformed gas supply system 11 electric valve 13 electric valve 16 electric valve 17 air supply system 18 electric valve 30 temperature detector 31 memory unit 32 control unit

Claims (2)

[Claims] 1. A phosphoric acid electrolyte for generating electricity by the hydrogen-rich reformed gas supplied from a carbon monoxide converter for converting carbon monoxide contained in a gas obtained by steam reforming a raw fuel and air supplied together with the hydrogen-rich reformed gas. In the fuel cell starting method, the temperature of the carbon monoxide shift converter and the fuel cell main body is raised at the time of starting, and the carbon monoxide concentration in the reformed gas delivered from the carbon monoxide shift converter and the fuel cell main body The temperature is measured, and when the carbon monoxide concentration reaches a concentration that does not give harmful poisoning to the electrode catalyst with respect to the temperature of the fuel cell body, it is necessary to supply reformed gas and air to the fuel cell body. Characteristic fuel cell startup method. 2. A phosphoric acid electrolyte for generating electricity by the hydrogen-rich reformed gas supplied from a carbon monoxide converter for converting carbon monoxide contained in a gas obtained by steam reforming a raw fuel and the air supplied together with the hydrogen-rich reformed gas. A fuel cell starter having the concentration detector for detecting the carbon monoxide concentration of the reformed gas delivered from the carbon monoxide shift converter, the temperature detector for detecting the temperature of the fuel cell body, and the fuel cell body A memory unit that stores the relationship between the temperature and the concentration of carbon monoxide that does not cause harmful poisoning to the electrode catalyst with respect to this temperature, and the signals of the concentration and temperature of carbon monoxide detected by the concentration detector and the temperature detector A fuel cell comprising: a control unit that opens valves provided in a supply system that respectively supplies reformed gas and air to the fuel cell based on the relationship input and read from the memory unit. Starter