JP6917744B2 - How to operate the fuel cell system - Google Patents

Description

The present invention is a fuel reforming apparatus that reforms raw fuel to generate a gas containing hydrogen as a main component, and a cell that generates power using a gas containing hydrogen as a main component generated by the fuel reforming apparatus. The fuel cell apparatus is provided with a reforming unit for reforming raw fuel to generate a reforming gas containing hydrogen as a main component and carbon monoxide, and the reforming gas. A metamorphic part having a carbon monoxide metamorphic catalyst that transforms carbon monoxide into carbon monoxide and carbon monoxide remaining in the modified gas discharged from the metamorphic part are selectively removed by oxidation. The present invention relates to an operation method of a fuel cell system having a carbon oxide removing unit.

Conventionally, the carbon monoxide remover converts carbon monoxide remaining in the modified gas into carbon dioxide by selectively oxidizing it with oxygen in the coexistence with a selective oxidation catalyst. Some were designed to remove carbon oxide (see, for example, Patent Document 1). The amount of oxygen supplied to the carbon monoxide removing section was maintained constant.

Japanese Patent No. 4162422

In the carbon monoxide removing section as described above, oxygen (air) needs to be supplied in order to oxidize the carbon monoxide remaining in the modified gas, but if oxygen is excessively supplied, Not only does it reduce processing efficiency, but it also raises the temperature due to the heat generated by the oxidation of carbon monoxide, and the methanation reaction between hydrogen and carbon dioxide may proceed in a chained manner, causing thermal runaway. The supply of carbon dioxide needs to be appropriate.

In addition, the selective oxidation catalyst for carbon monoxide as described above deteriorates due to aging and the oxidation treatment capacity decreases, and the catalyst is destroyed (powdered) due to thermal deformation of the catalyst container. Oxidation processing capacity may decrease.

By the way, it is conceivable to measure the content of carbon monoxide contained in the modified gas and adjust the oxygen supply amount based on the measurement, but it is possible to detect a minute amount of carbon monoxide. A possible high-precision and expensive carbon monoxide concentration sensor is required.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-precision carbon monoxide concentration sensor or the like separately and to satisfactorily oxidize carbon monoxide without complicating the configuration. The point is to provide a method of operating a fuel cell system that can be performed.

The characteristic configuration of the operation method of the fuel cell system according to the present invention for achieving the above object is a fuel reforming device that reforms raw fuel to generate a gas containing hydrogen as a main component, and the fuel reforming device. It is equipped with a fuel cell device having a cell that generates power using a gas containing hydrogen as a main component generated in
The fuel reformer reforms a raw material fuel to generate a reformed gas containing hydrogen as a main component and contains carbon monoxide, and transforms carbon monoxide contained in the reformed gas into carbon dioxide. A fuel cell having a metamorphic part having a carbon monoxide reforming catalyst and a carbon monoxide removing part for selectively removing carbon monoxide remaining in the reformed gas discharged from the reformed part by oxidation. How to operate the system
The voltage comparison step of comparing the output voltage of the cell before and after changing the operating condition of the carbon monoxide removing unit is performed while the output power of the fuel cell device is constant, and the output power of the fuel cell device is increased. Do it while it is at maximum output
Based on the result of the voltage comparison step, the output voltage of the cell under the first operating condition in which the oxidation of carbon monoxide in the carbon monoxide removing section is relatively promoted is set in the carbon monoxide removing section. When it is determined from the output voltage of the cell under the second operating condition that the oxidation of carbon monoxide is not relatively promoted, the second operating condition is changed to the subsequent operating condition of the carbon monoxide removing unit. The point is to perform the operation condition determination process.

According to the above characteristic configuration, in the voltage comparison step, the operating conditions of the carbon monoxide removing portion are changed, and the output voltage of the cell before the operating conditions are changed is compared with the output voltage of the cell after the change. .. The operating conditions include, for example, the amount of oxygen supplied to the carbon monoxide removing part and the temperature of the carbon monoxide removing part.

Then, when the operating conditions of the carbon monoxide removing unit change and the generated voltage of the cell in the fuel cell device changes, the operating conditions are not appropriate and there is room for further increasing the generated voltage. Is expected. On the other hand, even if the operating conditions of the carbon monoxide removing unit change, if the output voltage of the cell does not fluctuate, it is assumed that the operating conditions are appropriate.

Therefore, in the operating condition determination step, when the operating condition of the carbon monoxide removing unit changes from the first operating condition to the second operating condition, the output voltage of the cell under the first operating condition becomes the cell under the second operating condition. If it is determined from the output voltage of the above that it is within the set range, then the operating conditions are set so that the carbon monoxide removing unit is operated under the second operating condition. In this case, if, for example, a condition having the maximum oxidizing capacity is set as the first operating condition, the second operating condition exhibits a performance close to the maximum capacity among the operating conditions capable of performing an appropriate oxidation treatment. It is possible to set appropriate operating conditions such as being in a state.

Therefore, based on the change in the output voltage of the cell that fluctuates depending on the operating condition of the carbon monoxide removing unit, it is possible to determine whether or not the operating condition of the carbon monoxide removing unit at that time is appropriate, thereby achieving high accuracy. It has become possible to provide an operation method of a fuel cell system capable of satisfactorily oxidizing carbon monoxide without complicating the configuration by separately providing a carbon monoxide concentration sensor or the like.
Further, if the fuel cell device has the maximum output, the generated voltage of the cell also becomes a high value. As a result, when the operating conditions of the carbon monoxide removing unit change, the fluctuation of the power generation voltage of the cell also becomes large, and it becomes easy to compare the difference in the power generation voltage of the cell with respect to the change of the operating conditions in the voltage comparison process. ..

Another characteristic configuration of the operation method of the fuel cell system according to the present invention is
Based on the result of the voltage comparison step, it is determined that the output voltage of the cell under the first operating condition is larger than the set range from the output voltage of the cell under the second operating condition.
The above before and after changing the operating conditions of the carbon monoxide removing unit by changing the oxidation of carbon monoxide in the carbon monoxide removing unit to a third operating condition in which the oxidation of carbon monoxide is further promoted than the first operating condition. The point is that the voltage comparison step of comparing the output voltages of cells is performed.

According to the above characteristic configuration, if the output voltage of the cell under the first operating condition is larger than the set range from the output voltage of the cell under the second operating condition in the operating condition determination step, carbon monoxide is further oxidized. It is considered that there is room for improvement in performance to promote it. Therefore, the carbon monoxide is changed to a third operating condition in which the oxidation of carbon monoxide is further promoted than the first operating condition, and the output voltage is compared before and after the change. At that time, if the output voltage of the cell does not fluctuate, the operation is performed under the third operating condition. In this case, for example, if a condition having a low oxidizing ability is set as the first operating condition, the third operating condition can be an operating condition in which the appropriate oxidation treatment performance is enhanced, and is an appropriate operating condition. It becomes possible to.

As a result, it has become possible to satisfactorily oxidize carbon monoxide in a state where the oxidation of carbon monoxide is further promoted.

Yet another characteristic configuration of the operating method of the fuel cell system according to the present invention is that the operating condition is the amount of oxygen per unit time supplied to the carbon monoxide removing unit.

According to the above characteristic configuration, the amount of oxygen supplied to the carbon monoxide removing unit per unit time is changed as an operating condition, and the output voltage of the cell before and after the change is compared. When the amount of oxygen supplied is large, carbon monoxide is easily oxidized, and when the amount of oxygen supplied is small, it is difficult to oxidize carbon monoxide. Therefore, the amount of oxygen supplied directly affects the power generation performance of the cell. give. Therefore, it is easy to detect a change in the generated voltage of the cell due to a change in operating conditions.

Yet another characteristic configuration of the operating method of the fuel cell system according to the present invention is that the operating condition is the temperature of the carbon monoxide removing portion.

According to the above characteristic configuration, the temperature of the carbon monoxide removing portion is changed as an operating condition, and the output voltage of the cell before and after the change is compared. In the carbon monoxide removing section, the oxidation treatment of carbon monoxide is likely to be promoted when the temperature is high, and the oxidation treatment of carbon monoxide is difficult to be promoted when the temperature is low. Therefore, the temperature directly affects the power generation performance of the cell. give. Therefore, it is easy to detect a change in the generated voltage of the cell due to a change in operating conditions.

It is a figure which shows the structure of the fuel cell system. It is a figure explaining the structure of a cell. It is a flowchart explaining the operation method. It is a figure which shows the change state of the average cell voltage. It is a figure which shows the change state of the average cell voltage.

The operation method of the fuel cell system according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a fuel cell system. As shown in the figure, the fuel cell system is a modification supplied from a fuel reforming device 10 and a fuel reforming device 10 that reform a raw fuel gas containing hydrocarbons to generate a reforming gas containing hydrogen as a main component. It includes a fuel cell device 20 that uses quality gas as fuel to generate power, and an operation control device 1 that controls the operation of the fuel reforming device 10 and the fuel cell device 20.

The fuel reformer 10 includes a desulfurization unit 11, a reforming unit 12, a combustion unit 13, a transformation unit 14, a carbon monoxide removing unit 15, a steam generating unit 16, and a heat exchange unit 17.

The desulfurization section 11 is provided in the middle of the raw fuel gas flow path L1 for supplying the raw fuel gas containing hydrocarbons to the reforming section 12, and is included as an odorant in the supplied raw fuel (for example, city gas). Desulfurize the sulfur compound. The amount of raw fuel gas supplied to the desulfurization unit 11, that is, the amount of raw fuel supplied to the reforming unit 12, is such that the operation control device 1 is provided in the raw material fuel gas flow path L1 on the upstream side of the desulfurization unit 11. Adjust using the first valve V1. Further, the desulfurization unit 11 includes a temperature control means 11a for adjusting the temperature of the contained desulfurization catalyst. The temperature controlling means 11a is, for example, an electric heater. Then, the operation control device 1 controls the operation of the temperature adjusting means 11a so that the temperature of the desulfurization unit 11 (desulfurization catalyst) becomes the target temperature.

The reforming unit 12 reforms the raw material fuel gas in the presence of steam to generate a reforming gas containing hydrogen as a main component. Specifically, the reforming unit 12 is supplied with steam and the raw fuel after the desulfurization treatment in a mixed state. Then, the reforming unit 12 steam reforms the raw material and fuel using the heat generated in the adjacent combustion unit 13, and has hydrogen as the main component, and carbon monoxide and carbon dioxide as by-products. Produces a reformed gas containing carbon. The reformed gas generated by the reforming treatment in the reforming unit 12 is sent out to the reforming gas flow path L2 on the downstream side of the reforming unit 12.

The combustion unit 13 burns a flammable gas to generate heat. As the flammable gas, as will be described later, the anode exhaust gas (gas containing hydrogen not consumed in the power generation reaction) discharged from the fuel electrode (not shown) of the fuel cell device 20 or the combustion gas flow path. Combustion fuel gas such as city gas supplied through L7, or a mixture of both of them can be used. Further, air (oxygen) for combustion of combustible gas is supplied to the combustion unit 13 via the combustion air flow path L9.

The metamorphic section 14 is provided in the middle of the reformed gas flow path L2, and is treated so as to reduce carbon monoxide contained in the reformed gas generated in the reformed section 12. Specifically, in the transformation section 14, carbon monoxide contained in the reforming gas generated in the reforming section 12 reacts with steam, and carbon monoxide is transformed into carbon dioxide. Further, the transformation unit 14 includes a temperature control means 14a for adjusting the temperature of the contained carbon monoxide transformation catalyst. The temperature controlling means 14a is composed of, for example, an electric heater, a heat exchanger, or the like. Then, the operation control device 1 controls the operation of the temperature adjusting means 14a so that the temperature of the metamorphic unit 14 (carbon monoxide metamorphic catalyst) becomes the target temperature.

The carbon monoxide removing unit 15 is provided in the middle of the reformed gas flow path L2, and houses the carbon monoxide removing catalyst inside. In the carbon monoxide removing unit 15, carbon monoxide remaining in the reformed gas after the transformation treatment is oxidatively removed by oxygen in the air to which the carbon monoxide is added. Oxidation air is supplied from the air supply blower 18 to the reformed gas flow path L2 on the upstream side of the carbon monoxide removing portion 15 via the oxidation air flow path L12. The result is a hydrogen-rich reformed gas with a very low carbon monoxide concentration. Further, the temperature adjusting means 15a for adjusting the temperature of the carbon monoxide removing unit 15, specifically, the temperature of the carbon monoxide removing catalyst is provided. The operation control device 1 operates the air supply blower 18 so that the amount of oxygen supplied to the carbon monoxide removing unit 15 per unit time, specifically, the supply amount of the air supply blower 18 becomes a set amount. To control. Further, the operation control device 1 controls the operation of the temperature adjusting means 15a so that the temperature of the carbon monoxide removing unit 15 (carbon monoxide removing catalyst) becomes the target temperature. The temperature control means 15a is composed of, for example, an electric heater, a heat exchanger, or the like.

If the temperature of the carbon monoxide removing catalyst is constant, the carbon monoxide removing unit 15 becomes more active as the supply amount of air for oxidation increases, and the oxidation of carbon monoxide is likely to be promoted. Further, if the supply amount of the carbon monoxide removing unit 15 is constant, the higher the temperature of the carbon monoxide removing catalyst, the higher the activity and the more easily the oxidation of carbon monoxide is promoted.

The reformed gas after the carbon monoxide concentration is reduced by the carbon monoxide removing unit 15 is supplied to the fuel cell device 20 via the reformed gas flow path L2. A second valve V2 capable of opening and closing the reformed gas flow path L2 between the carbon monoxide removing unit 15 and the fuel cell device 20 is provided.

The steam generation unit 16 evaporates the water supplied from the water supply path L10 using the heat discharged from the combustion unit 13 to supply steam to the reforming unit 12. Specifically, in the heat exchange unit 17 provided adjacent to the steam generation unit 16, the combustion exhaust gas discharged from the combustion unit 13 supplies heat to the reforming unit 12, and then the combustion exhaust gas flow path L4. Supplied via. Then, the heat of the combustion exhaust gas is transferred to the steam generating unit 16 and used for evaporation of water. The steam generated by the steam generation unit 16 passes through the steam flow path L11 and joins the raw material fuel gas flow path L1 on the downstream side of the desulfurization unit 11. As a result, steam and the raw fuel gas after the desulfurization treatment are mixed and supplied to the reforming unit 12. The operation control device 1 adjusts the amount of water supplied to the steam generating unit 16, that is, the amount of steam supplied to the reforming unit 12.

The fuel cell device 20 is a solid polymer fuel cell, and as shown in FIG. 2, the cell C has an electrolyte membrane 22 made of a solid polymer sandwiched between a fuel electrode 23 (anode) and an oxygen electrode 24 (cathode). Is configured.

The fuel electrode 23 includes a gas diffusion layer 23a and a catalyst layer 23b, and the fuel gas supplied to the fuel gas flow path 26a formed on one surface of the first separator 26 on the side facing the gas diffusion layer 23a is the gas diffusion layer. It reaches the catalyst layer 23b through 23a. The catalyst layer 23b is composed of a carrier carrying a metal catalyst. Similarly, the oxygen electrode 24 includes a gas diffusion layer 24a and a catalyst layer 24b, and oxygen (air) supplied to an air flow path 27a formed on one surface of a second separator 27 on the side facing the gas diffusion layer 24a. Reach the catalyst layer 24b through the gas diffusion layer 24a. A cooling water flow path 27b through which cooling water flows is formed between the second separator 27 and the first separator 26 of the adjacent cell C.

The fuel cell device 20 is provided with a cell stack 25 formed by stacking a plurality of cells C as described above. As shown in FIG. 1, the reformed gas is supplied to the fuel electrode 23 of the cell stack 25 via the reformed gas flow path L2, and the oxygen electrode 24 of the cell stack 25 is supplied with the oxidant gas flow path L5. Oxygen (air) is supplied via the above to carry out a power generation reaction. The output power of the cell stack 21 (that is, the amount of power generation reaction) is adjusted by the operation control device 1 using an inverter (not shown), and the power is supplied to the power consuming device (not shown). Of the hydrogen supplied to the cell stack 25, excess hydrogen is discharged from the fuel electrode 23 of the cell stack 25 without being consumed by the power generation reaction in the cell stack 25, and passes through the anode exhaust gas flow path L3. It is supplied to the combustion unit 13 and burned as a combustible gas. The anode exhaust gas flow path L3 is provided with a third valve V3 capable of opening and closing the flow path, and is connected to the combustion gas flow path L7. The amount of combustion fuel gas supplied to the anode exhaust gas flow path L3 is adjusted by the operation control device 1 using a fourth valve V4 provided in the middle of the combustion gas flow path L7. The cathode exhaust gas discharged from the oxygen electrode 24 of the cell stack 25 is exhausted through the cathode exhaust gas flow path L6.

An intermediate portion of the reformed gas flow path L2 between the carbon monoxide removing portion 15 and its second valve V2 and an intermediate portion of the anode exhaust gas flow path L3 are connected by a bypass flow path L8. The bypass flow path L8 is provided with a fifth valve V5 capable of opening and closing the flow path.

When the operation of the fuel cell system is stopped, all of the above valves V1 to V5 are closed, and the area inside the fuel reformer 10 is stored, for example, in a state of being filled with raw fuel gas, and the cell stack. The inner region of 21 is stored, for example, filled with reforming gas.

When the operation of the fuel cell system is started, the operation control device 1 opens the first valve V1 to supply the raw fuel gas to the desulfurization unit 11, supplies water to the steam generation unit 16, and opens the fourth valve V4. Then, the combustion fuel gas is supplied to the combustion unit 13 via the combustion gas flow path L7 and the anode exhaust gas flow path L3 to operate the combustion unit 13 for combustion. Further, the operation control device 1 heats and operates the temperature control means 11a of the desulfurization section 11, the temperature control means 14a of the transformation section 14, and the temperature control means 15a of the carbon monoxide removing section 15, and the desulfurization section 11 and the transformation section 14 are operated. And the temperature of the carbon monoxide removing unit 15 is raised.

At the time when the operation is started, the operation control device 1 closes the second valve V2 and opens the third valve V3. As a result, the reformed gas generated in the reforming section 12 is not supplied to the fuel cell device 20, and the entire amount is burned in the combustion section 13 through the bypass flow path L8 and the anode exhaust gas flow path L3. The operation control device 1 continues to operate in this state. For example, when the temperature of the reforming catalyst reaches the set temperature by the temperature sensor T1 provided in the reforming unit 12, the starting process of the fuel reforming device 10 is completed. It is determined that the product has been used. Then, the operation control device 1 opens the second valve V2 and closes the third valve V3 so that the entire amount of the reformed gas generated by the reforming unit 12 is supplied to the fuel cell device 20. .. Further, the operation control device 1 appropriately adjusts the amount of combustion fuel gas supplied through the combustion gas flow path L7 so that the detection temperature of the temperature sensor T2 provided in the combustion unit 13 becomes a predetermined temperature, for example. Adjust.

The operation control device 1 is configured to execute a setting process for operating the carbon monoxide removing unit 15 under appropriate operating conditions. That is, the operation control device 1 executes the voltage comparison step, the determination step, and the operation condition determination step as the above setting process, as shown in FIG.

To add an explanation, the operation control device 1 performs a voltage comparison step of comparing the output voltage of the cell C before and after changing the operating conditions of the carbon monoxide removing unit 15, and the output power of the fuel cell device 20 is constant. Based on the result of the voltage comparison step, the output voltage of the cell C under the first operating condition in which the oxidation of carbon monoxide in the carbon monoxide removing unit 15 is relatively promoted is the carbon monoxide removing. When it is determined from the output voltage of the cell C under the second operating condition that the oxidation of carbon monoxide in the part 15 is not relatively promoted, the second operating condition is set to the subsequent carbon monoxide removing part 15. It is configured to perform an operating condition determination process that is determined as an operating condition.

The operation condition setting process as described above is performed periodically at appropriate intervals. For example, it is performed about once a month. The operation condition setting process is performed in a state where the output power of the fuel cell device 20 is adjusted to the maximum output, the operation is continuously performed at the maximum output for 1 hour, and then the output is stable.

When executing such an operation condition setting process, the operation control device 1 determines the amount of oxygen per unit time supplied to the carbon monoxide removing unit 15 as the operating condition of the carbon monoxide removing unit 15, specifically, the oxygen amount per unit time. , The amount of air for oxidation to the carbon monoxide removing unit 15 is changed. That is, the operation control device 1 changes the supply amount of the oxidizing air to the carbon monoxide removing unit 15 in the voltage comparison step, and detects the output voltage of the cell C before and after the change.

The specific operation will be described below.
FIGS. 4 and 5 show specific examples of changes in the output voltage of cell C when the supply amount of oxidizing air is changed. As the initial setting conditions of the carbon monoxide removing unit 15, for example, the temperature of the carbon monoxide removing catalyst is 90 ° C., and the supply amount of air for oxidation is 350 [ml / min]. In the example shown in FIG. 4, the operation control device 1 has an upper limit value that can adjust the supply amount of air for oxidation while maintaining the temperature of the carbon monoxide removal catalyst at 90 ° C., that is, 500 [ml] in the voltage comparison step. / Minute] is set. At this time, as the supply amount of the oxidizing air increases, the average value of the output powers of the plurality of cells C (hereinafter referred to as the average cell voltage) changes from 750 [mV] to 760 [mV]. Next, the supply amount of the oxidizing air is set to 400 [ml / min], and the average cell voltage before and after that is compared.

Then, in the determination step, before and after the change when the supply amount of the oxidizing air changes from 500 [ml / min] to 400 [ml / min], the output of the cell C at the time of supplying 500 [ml / min]. It is determined whether or not the voltage is within the set range from the output voltage of the cell C when 400 [ml / min] is supplied. In other words, it is determined whether or not the average cell voltage has fluctuated by a set amount or more.

In the example shown in FIG. 4, when the supply amount of the oxidizing air changes from 500 [ml / min] to 400 [ml / min], the average cell voltage changes to 750 [mV]. In this case, it can be assumed that the state in which the supply amount of the oxidizing air is set to 400 [ml / min] is not an appropriate operating state and the performance is not sufficiently exhibited. Therefore, in this case, the supply amount of the oxidizing air is set to 450 [ml / min], which is a set amount (50 [mV]) larger than 400 [ml / min], and the subsequent operation is executed. ing. In the example shown in FIG. 4, when the supply amount of the oxidizing air changes from 400 [ml / min] to 450 [ml / min], the average cell voltage changes to 760 [mV].

That is, under the operating conditions in which the supply amount of oxidizing air is set to the adjustable upper limit value (500 [ml / min]), the air supply amount becomes excessive, but 400 [ml / min] is insufficient. Therefore, by setting it to 450 [ml / min], it is possible to exhibit performance close to the maximum capacity.

On the other hand, in the example shown in FIG. 5, the supply amount of the oxidizing air is once set from 350 [ml / min] to 500 [ml / min] (first operating condition), and then the supply amount of the oxidizing air is set. Even when changed to 400 [ml / min] (second operating condition), the average cell voltage was constant at 760 [mV] and did not change. In this case, it is assumed that the state in which the supply amount of the oxidizing air is set to 400 [ml / min] is the proper operating state. Therefore, in this case, the subsequent operation is executed while maintaining the supply amount of the oxidizing air at 400 [ml / min]. In this example, 400 [ml / min] is in a state where the performance close to the maximum capacity is exhibited.

That is, in the above-mentioned treatment method, the supply amount of the oxidizing air is set to 500 [ml / min], which corresponds to the first setting condition, and the supply amount of the oxidizing air is set to 400 [ml / min]. It corresponds to the second setting condition.

In the treatment method for changing the supply amount of the oxidation air, in the above example, after setting the supply amount of the oxidation air to an adjustable upper limit value, the supply amount of the oxidation air is set to the set amount (50 [ml / min). ]), But it is not limited to 50 [ml / min], and it may be changed by a set amount smaller than that to more accurately adjust the capacity of the oxidation treatment. Further, instead of the method of reducing the supply amount of the oxidizing air, the supply amount of the oxidizing air may be set to be small in advance and changed so as to increase by the set amount.

Numerical values such as the temperature of the carbon monoxide removal catalyst, the supply amount of air for oxidation, and the average cell voltage shown in this embodiment are examples, and the present invention is not limited to these numerical values and is different. You can set it to a value and execute the process.

<Another Embodiment>
Next, another embodiment will be described.

<1>
In the above embodiment, as the operating condition of the carbon monoxide removing unit 15, the amount of air for oxidation to the carbon monoxide removing unit 15 is changed, but instead of this configuration, the carbon monoxide removing unit 15 As an operating condition, the temperature of the carbon monoxide removing unit 15 may be changed.

That is, in the voltage comparison step, the operation control device 1 changes the temperature of the carbon monoxide removing unit 15 as an operating condition of the carbon monoxide removing unit 15, and detects the output voltage of the cell C before and after the change.

Explaining the specific operation, as the initial setting conditions of the carbon monoxide removing unit 15, for example, the temperature of the carbon monoxide removing unit 15 is 90 ° C. and the supply amount of air for oxidation is 350, as in the above embodiment. [Ml / min] is set. The average cell voltage at this time is 700 [mV].

The operation control device 1 keeps the supply amount of air for oxidation at 350 [ml / min] and raises the temperature of the carbon monoxide removing unit 15 (specifically, the carbon monoxide removing catalyst) from 90 ° C. to 92 ° C. Change to. For example, as shown in Table 1, the carbon monoxide removing unit 15 improves the activity of the oxidation treatment as the temperature rises, so that the average cell voltage changes. In the example shown in Table 1, for example, the average cell voltage changes from 700 [mV] to 702 [mV]. Hereinafter, the temperature of the carbon monoxide removing unit 15 is changed and set so as to be increased by 2 ° C. At this time, for example, as shown in Table 1, when the temperature of the carbon monoxide removing unit 15 is changed from 92 ° C. to 94 ° C., the average cell voltage changes from 702 [mV] to 705 [mV], and carbon monoxide is carbon monoxide. When the temperature of the removing unit 15 is changed from 94 ° C. to 96 ° C., the average cell voltage is 705 [mV], indicating a case where the temperature has not changed since 94 ° C.

In the above-mentioned treatment method for changing the temperature of the carbon monoxide removing catalyst, the state where the temperature of the carbon monoxide removing unit 15 is set to 92 ° C. corresponds to the first operating condition in which the oxidation of carbon monoxide is relatively promoted. do. The state in which the temperature of the carbon monoxide removing unit 15 is set to 90 ° C. corresponds to the second operating condition in which the oxidation of carbon monoxide is not relatively promoted. The state in which the temperature of the carbon monoxide removing unit 15 is set to 94 ° C. corresponds to the third operating condition.

To add an explanation, the difference in cell output voltage between the state where the temperature of the carbon monoxide removing unit 15 is set to 92 ° C. and the state where the temperature of the carbon monoxide removing unit 15 is set to 90 ° C. is larger than the set range. The temperature of the carbon monoxide removing unit 15 is set to 94 ° C. as a third operating condition, which is large and further promotes oxidation than the first operating condition. Then, even if the temperature of the carbon monoxide removing unit 15 is further increased from 94 ° C., the output voltage of the cell C does not change, so that the subsequent operation is performed with the temperature of the carbon monoxide removing unit 15 set to 94 ° C. Set as a condition.

In the treatment method for changing the temperature of the carbon monoxide removing unit 15, in the above example, the temperature of the carbon monoxide removing unit 15 is increased by a set temperature (2 ° C.) from a lower temperature (90 ° C.). However, the temperature is not limited to 2 ° C., and the set temperature may be changed to a lower set temperature (1 ° C.) or a larger set temperature (3 ° C. or higher). Further, instead of the method of raising the temperature of the carbon monoxide removing unit 15, the temperature of the carbon monoxide removing unit 15 may be set high in advance and changed so as to decrease by the set temperature. When raising the temperature of the carbon monoxide removing unit 15, an upper limit temperature (for example, 100 ° C.) is set in order to avoid the occurrence of thermal run and the like, and the upper limit temperature is set so as not to be raised above the upper limit temperature. It is good to do.

Numerical values such as the temperature of the carbon monoxide removing unit 15, the supply amount of air for oxidation, and the average cell voltage shown in the present embodiment are examples, and the present invention is not limited to these numerical values. The process can be executed by setting different values.

< 2 >
In each of the above embodiments, as the initial setting conditions of the carbon monoxide removing unit 15, the temperature of the carbon monoxide removing unit 15 is set to 90 ° C., and the supply amount of air for oxidation is set to 350 [ml / min]. Although shown, instead of this configuration, for example, as shown in Table 2, the initial setting conditions may be changed according to the length of the integrated operation time of the fuel cell system.

The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

The present invention can be used in fuel cell systems.

10 Fuel reformer 12 Reformer 14 Metamorphic section 15 Carbon monoxide removal section 20 Fuel cell device

Claims (4)

A fuel cell having a fuel reformer that reforms raw fuel to generate a gas containing hydrogen as a main component and a cell that generates power using a gas containing hydrogen as a main component generated by the fuel reformer. Equipped with equipment,
The fuel reformer reforms a raw material fuel to generate a reformed gas containing hydrogen as a main component and contains carbon monoxide, and transforms carbon monoxide contained in the reformed gas into carbon dioxide. A fuel cell having a metamorphic part having a carbon monoxide reforming catalyst and a carbon monoxide removing part for selectively removing carbon monoxide remaining in the reformed gas discharged from the reformed part by oxidation. How to operate the system
The voltage comparison step of comparing the output voltage of the cell before and after changing the operating condition of the carbon monoxide removing unit is performed while the output power of the fuel cell device is constant, and the output power of the fuel cell device is increased. Do it while it is at maximum output
Based on the result of the voltage comparison step, the output voltage of the cell under the first operating condition in which the oxidation of carbon monoxide in the carbon monoxide removing section is relatively promoted is set in the carbon monoxide removing section. When it is determined from the output voltage of the cell under the second operating condition that the oxidation of carbon monoxide is not relatively promoted, the second operating condition is changed to the subsequent operating condition of the carbon monoxide removing unit. A method of operating a fuel cell system that performs a process of determining operating conditions. Based on the result of the voltage comparison step, it is determined that the output voltage of the cell under the first operating condition is larger than the set range from the output voltage of the cell under the second operating condition.
The above before and after changing the operating conditions of the carbon monoxide removing unit by changing the oxidation of carbon monoxide in the carbon monoxide removing unit to a third operating condition in which the oxidation of carbon monoxide is further promoted than the first operating condition. The method for operating a fuel cell system according to claim 1, wherein the voltage comparison step of comparing the output voltages of cells is performed. The method for operating a fuel cell system according to claim 1 or 2, wherein the operating condition is an amount of oxygen per unit time supplied to the carbon monoxide removing unit. The method for operating a fuel cell system according to claim 1 or 2, wherein the operating condition is the temperature of the carbon monoxide removing unit.

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