JP2002042850A - Operation method for fuel cell generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover the power generation efficiency reduced by CO slightly contained in fuel gas in time course by providing a stopping method in abnormality for a fuel cell device eliminated from lowering the power generating efficiency after recovery by damage of CO. SOLUTION: When temperature abnormality of a hydrogen generator 2 is detected by a reforming part temperature measuring means 10, a CO degeneration part temperature measuring means 11, and a CO oxidation removal part temperature measuring means 12, when a raw material inputted in the hydrogen generator 2 is detected to become excessive by a raw material flow meter 5, or when the water volume inputted in the hydrogen generator 2 is detected to be reduced by the degeneration water flow meter 16, the power generating operation is made to stop and the air is inputted in a fuel electrode side of the fuel cell stack for a prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stopping a power generation operation of a power generator including a hydrogen generator and a solid polymer electrolyte fuel cell when the hydrogen generator is abnormal.

[0002]

2. Description of the Related Art Normally, fuel cells use city gas or hydrogen gas generated by reforming a hydrocarbon-based material such as methanol as a fuel gas. However, particularly in the case of a polymer electrolyte fuel cell (hereinafter abbreviated as “PEFC”),
Since a platinum catalyst is usually used for the fuel electrode, the platinum catalyst is poisoned by a trace amount of carbon monoxide contained in the fuel gas, the catalytic activity is reduced, and the cell performance is greatly deteriorated. Therefore, as a method of reducing the CO concentration in the fuel gas, a so-called CO shift method has been proposed. In this method, methanol or city gas is steam reformed, and CO is removed from the reformed gas obtained using a CO shift catalyst. Then, oxygen (air) is introduced again into the gas after CO conversion, and CO is further oxidized and removed at 200 to 300 ° C. using an oxidation catalyst. Such modification, following the procedure of CO-modified and CO oxidation removal, hydrogen generator for generating hydrogen containing CO and CO ₂ in the reduced trace to a level no problem when the power generation of the fuel cell, solid It is widely used in polymer fuel cell power generators.

In order for the above-mentioned CO removal to function effectively,
It is necessary to appropriately control the reaction temperature of the steam reforming reaction, the CO reforming reaction and the CO oxidation reaction, and the amount of steam supplied. When these parameters deviate from the appropriate ranges, the catalyst at the anode in the fuel cell stack is poisoned by the CO that has not been sufficiently removed, causing a great decrease in the cell performance. Also, when the amount of the hydrocarbon-based raw material supplied to the hydrogen generator increases for some reason, CO is generated, and similarly, the battery performance is reduced. On the other hand, during operation of the fuel cell power generator, if the temperature of the hydrogen generator, the amount of input water and the amount of input raw material deviate from the normal range due to accidental disturbance or component failure, the power generator is turned off. In many cases, it is determined that the power generation device is in an abnormal state, and measures are taken to stop the power generation operation of the power generation device.

[0004]

Further, once the battery performance is reduced due to CO poisoning, the battery performance does not recover as it is. Therefore, if it is detected that the temperature of the hydrogen generator, the input water amount, the input raw material amount, and the like deviate from the appropriate ranges, and the power generation operation is stopped, the fuel-side catalyst of the fuel cell may be poisoned by CO. high. In this case, since the CO poisoning state remains after the power generation is stopped, there is a problem that sufficient performance cannot be exhibited when the power generation device is restarted after performing necessary measures. is there. In order to solve such a problem, for example, JP-A-11-40178 and JP-A-11-345
No. 624 proposes a method of removing the influence of CO poisoning while performing a power generation operation of a fuel cell power generator. However, in these methods, CO concentrations in the order of tens to hundreds of ppm are assumed,
It is not suitable when a large amount of CO of several percent level is instantaneously generated due to abnormal operation of the hydrogen generator and the fuel-side catalyst of the fuel cell is poisoned.

At present, there is no effective method for detecting low-concentration CO. Therefore, there is no effective means for grasping that the catalyst on the fuel electrode side of the fuel cell is poisoning CO. There is also a problem that recovery treatment by CO oxidation cannot be performed. On the other hand, a method of judging CO poisoning by lowering the cell voltage of a fuel cell has also been proposed, but the cell voltage is determined by changing the cell temperature, the fuel gas flow rate, the oxidizing gas flow rate, and the fuel gas or dew condensation water. The determination is difficult because it is affected by many factors such as a partial supply shortage of the oxidizing gas. Furthermore, at present, there is a problem that the voltage at the same current density of the fuel cell stack decreases with time due to CO slightly contained in the fuel gas, and the power generation efficiency gradually decreases. Therefore,
An object of the present invention is to realize a method of operating a fuel cell power generation device at the time of an abnormality in which power generation efficiency after recovery is not reduced due to CO poisoning. Another object of the present invention is to restore the power generation efficiency of the fuel cell power generation device, which decreases with time due to CO slightly contained in the fuel gas.

[0006]

In order to solve the above problems, the present invention provides a hydrogen generator for producing a fuel gas containing hydrogen as a main component from a hydrocarbon-based raw material and water; A solid polymer electrolyte fuel cell stack that generates electric power by using a gas, wherein (a) the temperature of the hydrogen generator and the hydrogen generator When at least one selected from the group consisting of the amount of water to be charged and the hydrocarbon-based raw material to be charged to the hydrogen generator deviates from a predetermined range, the power generation is stopped, and (b) the solid height is reduced. Provided is a method of operating a fuel cell power generator in which a fuel gas flow channel of a molecular electrolyte fuel cell stack is purged with an inert gas, and (c) air or oxygen flows through the fuel gas flow channel for a predetermined time. .

Further, the present invention provides a hydrogen generator for generating a fuel gas containing hydrogen as a main component from a hydrocarbon-based raw material and water, and a solid polymer electrolyte type fuel for generating electricity using the fuel gas and an oxidizing gas. (A ′) stopping the power generation when the total power generation operation time or the number of times of power generation of the fuel cell power generation device exceeds a predetermined value, and (b) the solid height. Also provided is a method of operating a fuel cell power generator in which a fuel gas flow channel of a molecular electrolyte fuel cell stack is purged with an inert gas, and (c) air or oxygen flows through the fuel gas flow channel for a predetermined time. I do. In the step (c), air or oxygen is
The flow is preferably performed for at least 5 minutes, more preferably for at least 5 minutes.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited thereto. << Embodiment 1 >> FIG. 1 is a configuration diagram of a polymer electrolyte fuel cell power generator according to Embodiment 1 of the present invention.
The configuration and operation of the polymer electrolyte fuel cell power generator shown in FIG. 1 will be described below. The polymer electrolyte fuel cell power generation device according to the present embodiment is a polymer electrolyte fuel cell stack 1 that generates power using a fuel gas and an oxidizing gas, and a steam reforming of raw materials such as natural gas. A hydrogen generator 2 for generating a hydrogen-rich gas and supplying it to the fuel cell stack 1;
A blower 3 of a centrifugal type as an oxidizing gas supply device for supplying the oxidizing gas. The hydrogen generator 2 by the raw material supply means 4
The amount of the raw material to be charged into the container is measured by the raw material flow meter 5.

The hydrogen generator 2 comprises a steam reforming section 6, a CO modifying section 7, and a CO oxidation removing section 8. The steam reforming section 6 includes a reforming section heating means 9. Further, as means for measuring the temperature in the reaction chamber of each unit, a reforming unit temperature measuring unit 10 and a CO denaturing unit temperature measuring unit 1 are respectively provided.
1 and a CO oxidation removing section temperature measuring means 12. The steam reforming unit 6 and the CO denaturing unit 7 pass through a reforming water flow meter 15 and a denaturing water flow meter 16 respectively, and then a reforming unit water supply pump 13 and a CO denaturing unit water supply pump 14.
To supply the required amount of water. In addition, a necessary amount of air is introduced into the CO oxidation removing unit 8 by the CO oxidation removing unit air pump 17. The steam reforming unit 6, the CO denaturing unit 7, and the CO oxidation removing unit 8 each include a reforming unit cooling fan 18, a CO denaturing unit cooling fan 19 as cooling means.
And a cooling fan 20 for removing the CO oxidation.

Air serving as an oxidizing gas is supplied to the positive electrode of the unit cell constituting the fuel cell stack 1, and a fuel gas rich in hydrogen generated by the hydrogen generator 2 is supplied to the negative electrode. Electric power is generated by the chemical combination of oxygen and hydrogen. In the hydrogen generator 2, a gas rich in hydrogen is generated as follows. First, hydrogen, CO ₂ and CO are produced from the raw material gas by the steam reforming section 6.
Next, these gases are sent to the CO modification unit 7 and further CO 2
And water produce hydrogen and CO ₂ . Next, the CO is sent to the CO oxidation removing section 8, and the remaining CO is further removed. According to this method, the CO concentration can be reduced to a concentration that does not cause any problem in operating the polymer electrolyte fuel cell power generator. At this time, since the reaction chamber temperatures of the steam reforming section 6, the CO denaturing section 7, and the CO oxidation removing section 8 need to be within appropriate ranges, the reforming section temperature measuring means 10, the CO denaturing section temperature measuring means 11, On the basis of the output signals of the CO oxidation removal section temperature measuring means 12 and the raw material flow meter 5, the reforming section heating means 9, the reforming section cooling fan 18, the CO denaturing section cooling fan 19, and the CO
By controlling the operation capacity of the oxidation removing section cooling fan 20, the temperature of the reaction chamber can be maintained within an appropriate range. Here, if it deviates from the appropriate range, the fuel cell power generator shifts to a power generation emergency stop operation.

Here, a "predetermined range" for the temperature of the hydrogen generator, the amount of water supplied to the hydrogen generator, and the amount of hydrocarbon-based fuel supplied to the hydrogen generator.
Varies depending on the configuration of the hydrogen generator to be used, the type of the hydrocarbon-based raw material and the catalyst, the position of temperature measurement, and the like. However, if a person skilled in the art knows the configuration of the hydrogen generator to be used, the type of the hydrocarbon-based raw material and the catalyst, and the position of the temperature measurement, the temperature of the hydrogen generator, the amount of water supplied to the hydrogen generator By controlling the amount of the hydrocarbon-based fuel supplied to the hydrogen generator, it is possible to suppress the generation of CO from the hydrogen generator. Therefore, the “predetermined range” in the present invention refers to the temperature of the hydrogen generator, the amount of water supplied to the hydrogen generator, and the amount of water supplied to the hydrogen generator when CO that causes deterioration of the fuel cell is not generated from the hydrogen generator. It refers to the range of the amount of hydrocarbon-based fuel to be charged. That is, if the temperature of the hydrogen generator, the amount of water supplied to the hydrogen generator, and the amount of the hydrocarbon-based fuel supplied to the hydrogen generator are within predetermined ranges, the generation of CO can be suppressed.

The amounts of the hydrocarbon-based raw material and water will be described below. Normally, when city gas (mainly containing methane) is used as a raw material, unless the amount of water is controlled so that the S / C (ratio of water and carbon in the raw material) becomes 2 or more in principle, C
O is generated. Also, when the amount of the source gas increases, the S / C falls below 2 and CO is generated. Furthermore, even when the amount of raw material gas is increased and the amount of water is increased so as to follow it, the reaction exceeds the capacity of the catalyst and the reaction cannot keep up with the amount of input gas, which also causes CO generation. Would. Here, S / C = 2 is used as a reference, but it is considered that CO generation cannot be avoided unless a larger value (for example, 3) is actually used. However, as described above, this value is considered to be device-dependent. When methanol is used as a raw material, in principle, S / C
= 1 is the theoretical value.

Next, the temperature will be described. Since the heat resistance temperature of the catalyst used in the denaturing section is usually about 500 ° C., if it exceeds this, the catalyst will be damaged and CO will be generated at the same time. When the temperature is lower than about 200 ° C., the reaction does not proceed, and CO is generated. In the purification section, the reaction equilibrium shifts to the CO generation side at about 250 ° C. or more, and CO is generated. At about 100 ° C. or less, the reaction does not take place, so CO is generated. Further, since the temperature of the hydrogen generation unit varies considerably depending on the type of catalyst and the measurement site, the predetermined range may be appropriately determined according to the difference in the configuration of the apparatus such as the measurement unit.

In the power generation emergency stop operation, after the power generation is stopped, hydrogen remains in the fuel gas flow path of the fuel cell stack, but after hydrogen is purged with nitrogen gas by nitrogen purging means (not shown). The air taken in from the CO oxidation removing unit air pump 17 is flowed for a predetermined time to complete the process. Here, a case where an abnormality occurs in one or both of the reforming unit water supply pump 13 and the CO denaturation unit water supply pump 14 will be considered. In this case, sufficient steam cannot be supplied to the steam reforming section 6 and / or the CO reforming section 7, and a large amount of CO is generated. At this time, the temperature of at least one of the steam reforming unit 6, the CO denaturing unit 7, and the CO oxidation removing unit 8 simultaneously rises, and the reforming unit temperature measuring unit 10, the CO denaturing unit temperature measuring unit, respectively. The temperature rise is detected by the temperature measurement means 11 and the CO oxidation removal unit temperature measurement means 12, and the power generation emergency stop operation is started. The fuel electrode catalyst poisoning of the fuel cell caused by the CO thus generated can be recovered by introducing air in the power generation emergency stop operation. Also, the reformed water flow meter 15 and the modified water flow meter 16 are not essential requirements of the present invention,
If these are provided, the reforming section water supply pump 1
Abnormality occurring in one or both of the water supply pump 14 and the CO-modified unit water supply pump 14 can be detected to start the power generation emergency stop operation.

Next, when an abnormality occurs in the reforming section heating means 9,
Consider a case in which the temperature of one of the steam reforming section 6, the CO modifying section 7, and the CO oxidation removing section 8 or a plurality of reaction chambers is lowered. In this case, the equilibrium of the reaction is inclined toward the CO generation side, and a large amount of CO is generated. Then, a temperature decrease is detected by the reforming unit temperature measuring unit 10, the CO denaturing unit temperature measuring unit 11, and the CO oxidation removing unit temperature measuring unit 12.
Therefore, when these temperatures fall below a certain lower limit, the above-mentioned power generation emergency stop operation is started. Thus, the generated C
The fuel-electrode catalyst poisoning of the fuel cell caused by O is recovered by the introduction of air in the power generation emergency stop operation.

Next, a case where an abnormality occurs in the raw material supply means 4 will be considered. When a raw material exceeding the limit that can be processed by the hydrogen generator 2 is supplied, CO cannot be sufficiently removed, and a large amount of CO is generated. In this case, the excessive flow of the raw material is detected by the raw material flow meter 5, and the power generation emergency stop operation is started. Thus, the poisoning of the fuel electrode catalyst of the fuel cell caused by the generated CO is recovered by the introduction of air in the power generation emergency stop operation.

Next, a case where an abnormality occurs in one or more of the reforming unit cooling fan 18, the CO denaturing unit cooling fan 19, and the CO oxidation removing unit cooling fan 20 will be considered. In this case, the temperature of one or more of the steam reforming unit 6, the CO denaturing unit 7, and the CO oxidation removing unit 8 or a plurality of reaction chambers rises, and the reforming unit temperature measuring unit 10, the CO denaturing unit temperature measuring unit 11, and the CO Oxidation removal section temperature measuring means 12
To detect the rise in temperature, and starts the power generation emergency stop operation. If the amount of supplied water is more than an appropriate amount, a large amount of CO does not occur, but from the viewpoint of preventing damage to the device, it is necessary to stop power generation. At this time, the operation of removing CO oxidation from the fuel electrode of the fuel cell by air purging is not necessary, but there is no harm to performing this operation.

In this case, in the power generation emergency stop operation, the air pump 17 is used as an air supply method.
However, air may be supplied through the bypass pipe 21 using the blower 3. The effect of the present invention can be similarly obtained by using other means (FIG. 2).
reference). Also, here, the steam reforming section 6, the CO reforming section 7
The reforming section temperature measuring means 10, the CO denaturing section temperature measuring means 11 and the CO
The configuration in which the temperature of the reaction chamber is measured by using the oxidation removal unit temperature measuring means 12 has been described. However, one or more of these temperature measuring means is omitted, and the temperature of the corresponding part is estimated from the temperature of the other part. The same effect can be obtained by using the method described above. Further, here, as cooling means for the steam reforming unit 6, the CO denaturing unit 7, and the CO oxidation removing unit 8, the reforming unit cooling fan 18, the CO denaturing unit cooling fan 1
Although the configuration using the cooling fan 9 and the CO oxidation removing unit cooling fan 20 has been described, the effects of the present invention can be similarly obtained by using other cooling means, for example, a method of circulating a coolant such as water. In addition, here, the configuration using the blower as the air supply means has been described, but the effects of the present invention can be similarly obtained by using other means having the same function.

<< Embodiment 2 >> The solid polymer electrolyte fuel cell power generator according to the present embodiment is different from that of the first embodiment in that a cumulative power generation operation time measuring means (not shown) is added.
This is the same as the solid polymer electrolyte fuel cell power generator according to Embodiment 1 described above. Therefore, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The solid polymer electrolyte fuel cell power generation device according to the present embodiment includes a cumulative power generation operation time measuring unit, which measures the power generation operation time. When the cumulative power generation operation time exceeds a predetermined value, unlike the first embodiment, the operation is continued until the power generation operation of the polymer electrolyte fuel cell power generation device is stopped, and the power generation operation is performed. After the shutdown, the nitrogen gas is purged with nitrogen gas by a nitrogen purge unit (not shown) into the fuel gas flow channel of the fuel cell stack, and then the air taken in from the CO oxidation removing unit air pump 17 flows for a predetermined time. At the same time, the accumulated power generation operation time held by the accumulated power generation operation time measuring means is returned to zero. By this operation, the fuel electrode catalyst poisoning of the fuel cell, which is generated by a minute amount of CO for a long time, is recovered by the introduction of air in the power generation emergency stop operation, and the power generation efficiency is recovered.

[0020]

As described above, according to the present invention, it is possible to realize a method of stopping the fuel cell device in the event of an abnormality without reducing the power generation efficiency after restoration due to CO poisoning due to an abnormality in the hydrogen generator. . Also, the CO contained in the fuel gas slightly
As a result, the power generation efficiency that decreases over time can be recovered.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a polymer electrolyte fuel cell power generator according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a polymer electrolyte fuel cell power generator according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel cell stack 2 hydrogen generator 3 blower 4 raw material supply means 5 raw material flow meter 6 steam reforming section 7 CO reforming section 8 CO oxidation removing section 9 reforming section heating means 10 reforming section temperature measuring means 11 CO reforming section temperature Measuring means 12 CO oxidation removing section temperature measuring means 13 Reforming section water supply pump 14 CO modifying section water supply pump 15 Reforming water flow meter 16 Denaturing water flow meter 17 CO oxidation removing section air pump 18 Reforming section cooling fan 19 CO Denaturing section cooling fan 20 CO oxidation removal section cooling fan 21 Bypass piping

Continuation of the front page (72) Inventor Tetsuya Ueda 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5H026 AA06 5H027 AA06 BA01 BA16 BA17 BA20 KK00 KK21 KK42 MM08

Claims (2)

[Claims] 1. A hydrogen generator for generating a fuel gas containing hydrogen as a main component from a hydrocarbon-based raw material and water, and a solid polymer electrolyte fuel cell stack for generating power using the fuel gas and an oxidizing gas. (A) The temperature of the hydrogen generator, the amount of water supplied to the hydrogen generator, and the carbonization supplied to the hydrogen generator during the power generation operation of the fuel cell power generator. A step of stopping the power generation when at least one selected from the group consisting of hydrogen-based raw materials deviates from a predetermined range; and (b) a failure in the fuel gas flow path of the solid polymer electrolyte fuel cell stack. A method for operating a fuel cell power generator, comprising: a step of purging with an active gas; and (c) a step of flowing air or oxygen into the fuel gas flow path for a predetermined time. 2. A hydrogen generator for generating a fuel gas containing hydrogen as a main component from a hydrocarbon-based raw material and water, and a solid polymer electrolyte fuel cell stack for generating electricity using the fuel gas and an oxidizing gas. (A ′) a step of stopping the power generation when the total power generation operation time or the number of times of power generation of the fuel cell power generation device exceeds a predetermined value, (b) the solid polymer electrolyte type A method of operating a fuel cell power generator, comprising: purging a fuel gas flow path of a fuel cell stack with an inert gas; and (c) flowing air or oxygen through the fuel gas flow path for a predetermined time.