JP2002075416A - Fuel cell device and operation method of fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell device which can well prevent a gas flow channel at an anode side of a fuel cell in operation from choking due to draining, and an operation method of same. SOLUTION: The fuel cell device 10 is provide with an exhaust gas supply line L7 with one end connected to an exhaust gas line L3 for discharging exhaust gas outside belched out of an anode of a fuel cell FC and the other end connected to a fuel gas supply line L1 combining a reformer 15 and the anode, a circulating bower B2 equipped on the exhaust gas supply line to supply the anode with a part of exhaust gas belched out of the anode, a flow regulation valve FRV4 adjusting supply volume of exhaust gas supplied to the anode, and a control means 90 for controlling the circulating blower B2 and the flow regulation valve 4 so that flow rate of the exhaust gas at the exit of the gas flow channel formed by the anode and a separator may be at a given value of 0.45 m/s according to load request made to the fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell device and a method for operating the same, and more particularly, to a fuel cell device for generating electric power by a fuel cell having a polymer electrolyte and a method for operating the same.

[0002]

2. Description of the Related Art A fuel cell directly extracts electric energy generated by an electrochemical reaction using a fuel gas (anode reaction gas) as an electrode active material and an oxidizing gas (a cathode reaction gas). Therefore, the fuel cell has high power generation efficiency in a low-temperature operation region. Therefore, according to the fuel cell device as a power generation unit equipped with a fuel cell, it is possible to achieve higher overall energy efficiency as compared with a heat engine that is restricted by Carnot efficiency, It is also easy to recover the thermal energy generated.

[0003] As an electrode active material and an electrolyte of a fuel cell, it is common to use hydrogen, oxygen, and a proton conductive electrolyte. The electrode reaction shown in equation (2) proceeds, and the whole battery reaction shown in equation (3) proceeds as a whole to generate an electromotive force. H ₂ → 2H ⁺ + 2e ⁻ (1) (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2) H ₂ + (1/2) O ₂ → H ₂ O (3)

Fuel cells that generate electric power by such an electrochemical reaction are classified according to electrode active materials, electrolytes, operating temperatures, and the like. Among them, a so-called polymer electrolyte type using a polymer electrolyte as an electrolyte is used. Fuel cell (P
EFC) is expected to be practically used as a power source for mobile vehicles such as electric vehicles and small cogeneration systems because it is easy to reduce the size and weight. In a polymer electrolyte fuel cell, a cation exchange membrane (solid polymer electrolyte membrane) having proton conductivity as an electrolyte is arranged between an anode serving as a gas diffusion electrode and a cathode to form a so-called single cell. Then, a hydrogen-containing gas generated by steam reforming a hydrocarbon-based raw fuel such as methanol or natural gas is used as the fuel gas, and air is used as the oxidizing gas.

[0005] A thin-plate separator made of a gas-impermeable conductive material is disposed on both the anode and cathode sides of the single cell. A groove serving as a flow path of a fuel gas or an oxidizing gas is formed on a contact surface of the separator with the electrode, and a fuel gas and an oxidizing gas supplied from the outside are provided at a predetermined rate in accordance with operating conditions of the fuel cell. Is supplied into this flow path at a flow rate of, and is supplied to the fine gas diffusion paths in the anode and the cathode while traveling from the inlet to the outlet in the flow path, and is consumed in the reaction (1) or (2), respectively. . In addition, the reaction product water and excess humidification water generated by the equation (3) are discharged to the outside together with the exhaust gas of the fuel gas or the oxidizing gas from the gas flow path. Further, when the fuel cell is a so-called stack, a groove serving as a flow path for a fuel gas or an oxidizing gas is formed on both surfaces of the separator to be used, and the unit cell and the separator are alternately arranged via a sealing material or the like as appropriate. Multiple layers are laminated.

In order to put such a polymer electrolyte fuel cell into practical use, it is extremely important to maintain good ionic conductivity of the solid polymer electrolyte membrane. The generated protons move through the electrolyte membrane with the water of hydration. On the contrary,
Since the whole battery reaction shown in the equation (3) is an exothermic reaction,
With the operation of the fuel cell, the temperature of the electrolyte membrane is increased and dried. Therefore, if the electrolyte membrane dries, the electrolyte resistance will necessarily increase, and the electrolyte is required to maintain the ion dissociation degree of the ion exchange groups present in the membrane and stabilize the performance of the fuel cell. It is necessary to sufficiently humidify the membrane.

[0007] Therefore, the fuel cell device usually has a structure for constantly humidifying the electrolyte membrane of the operating fuel cell. For example, a fuel gas or an oxidizing gas contains a water vapor component and is supplied to the anode and the cathode, respectively. A configuration that constantly humidifies the electrolyte membrane of the operating fuel cell by supplying it, and a configuration that supplies humidification water directly into the fuel cell by using a part of the cooling water of the fuel cell are adopted. I have.

[0008]

However, in the fuel cell device configured as described above, when the flow rate of the fuel gas or the oxidizing gas supplied to the fuel cell decreases, the generated reaction product water and excess water are generated. There has been a problem that it becomes difficult for the humidifying water to be quickly discharged to the outside together with the exhaust gas, and that such water stays in the gas passage of the separator and becomes a drain, thereby blocking the gas passage. If the gas flow path in the separator is blocked by the drain, the progress of the electrode reaction is hindered, and it becomes difficult to stably obtain a desired battery output.

Normally, the gas flow path of the separator is supposed to be an operating condition under which the load requirement is maximum, that is, a condition under which the flow rate of the flowing gas is maximum. Designed to be minimal.
Therefore, when the fuel cell is operated under relatively high load operating conditions, the drain generated in the gas flow path of the separator is quickly transported to the outside by the reaction gas having a large flow rate, which hinders operation. However, if the load demand on the fuel cell fluctuates and the fuel cell is operated under relatively low load demand operating conditions,
Since the flow rate of the reaction gas flowing in the gas flow path is low, the generated drain tends to stagnate in the gas flow path. Further, when the operation is performed for a long time, drain may gradually accumulate in the gas passage of the separator due to a change in load demand or a change in operating temperature.

[0010] Such a problem of blockage in the gas flow path due to drainage is particularly likely to occur in the gas flow path on the anode side. That is, air is usually used as the oxidizing gas, and the oxygen partial pressure is relatively low and the partial pressure of an inert gas such as nitrogen is high, so that the necessary amount of oxygen for the fuel cell cathode is required. When supplying gas, a large amount of inert gas is inevitably supplied in addition to oxygen. It is possible to easily set the flow rate of the oxidizing gas that can be transported to the outside without stagnation in the road.
On the other hand, the fuel gas is produced by reforming the fuel with steam in the reformer and then supplied to the anode. The hydrogen partial pressure is high, and the steam partial pressure is also the saturated steam pressure at the operating temperature of the fuel cell. If it is placed in an operating condition with a low load requirement because it is adjusted near and it is relatively high,
The flow rate of the fuel gas in the gas flow passage is significantly reduced, and the drain tends to stagnate in the gas flow passage.

Also, a high hydrogen utilization rate (for example, 80%)
It is important to operate the fuel cell under the above operating conditions in order to effectively use the hydrogen generated in the reformer. In this case, the flow rate of the fuel gas further decreases, and the drain tends to stagnate in the gas flow path on the anode side. Therefore, when putting the fuel cell device into practical use, it is necessary to pay attention to the prevention of the gas passage on the anode side from being blocked by the drain.

Accordingly, an object of the present invention is to provide a fuel cell device capable of sufficiently preventing the gas flow path on the anode side of an operating fuel cell from being clogged by a drain, and an operation method thereof.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, even if drain is generated in the gas flow path formed in the anode, the outlet of the gas flow path is not removed. It has been found that by adjusting the flow rate of the anode reaction gas supplied to the anode so that the flow rate at 0.45 m / s or more is at least 0.45 m / s, the gas can be quickly discharged from the outside of the gas flow path. Reached.

That is, the fuel cell device according to the present invention comprises:
A fuel cell in which a plurality of unit cells each having a polymer electrolyte and a separator disposed between an anode and a cathode are stacked, and an anode reaction gas generated by a reformer is supplied to the anode and a cathode reaction gas is supplied In a fuel cell device that supplies a cathode reaction gas to the cathode from the means and generates electric power by an electrochemical reaction, one end is connected to an exhaust gas line that discharges exhaust gas discharged from the anode to the outside, and the other end is connected to a reformer. An exhaust gas supply line connected to a gas line connecting the anode, an exhaust gas supply means provided on the exhaust gas supply line, for supplying a part of the exhaust gas discharged from the anode to the anode, and a load request for the fuel cell. The flow rate of the exhaust gas at the outlet of the gas flow path formed by the anode and the separator is 0.45 m / And a controlling means for controlling the exhaust gas supply means to a predetermined value or more.

This fuel cell device is suitable for use as a power source for a mobile vehicle or a home power generation unit or the like. A fuel cell has a polymer electrolyte disposed between an anode and a cathode. The separator is formed, for example, in a thin plate shape, and has a gas flow path for flowing an anode reaction gas (fuel gas) on the anode side surface, and a cathode reaction gas (oxidizing gas) on the cathode side surface. It has a gas flow path for making it.

Such a fuel cell has a reformer for supplying an anode reactant gas, a blower or a compressor for supplying a cathode reactant gas, and various other auxiliary equipment. An anode reaction gas (fuel gas) such as a generated hydrogen-containing gas is supplied. Further, a cathode reaction gas (oxidizing gas) such as air is supplied to the cathode of the fuel cell by a blower or the like. Thus, the anode reactant gas reacts at the anode and the cathode reactant gas reacts at the cathode, and a predetermined whole cell reaction proceeds in the whole fuel cell to obtain an electromotive force.

Here, during the operation of such a fuel cell device, the flow rates of fuel gas and air supplied to the fuel cell are:
It changes within a relatively wide range according to the change in the load demand for the fuel cell. Therefore, when the flow rate of the fuel gas is significantly reduced, for example, when operating under a low load requirement, as described above, the reaction product water and excess humidification water stay in the gas flow path of the anode separator. It is supposed that the gas flow path becomes drain and blocks the gas flow path.
In view of this point, the fuel cell device includes an exhaust gas supply line, exhaust gas supply means for supplying a part of exhaust gas discharged from the anode to the anode, and an anode and a separator based on a load request for the fuel cell. The flow rate of the exhaust gas at the outlet of the formed gas flow path is 0.45 m /
and control means for controlling the exhaust gas supply means so as to have a predetermined value of s or more.

With this configuration, even if drainage is generated in the gas flow path of the anode due to a decrease in the load demand on the fuel cell during operation of the fuel cell device, the drain is quickly removed. Since the gas can be discharged from the gas flow path to the outside, the fuel cell can be always operated in a stable state in accordance with the load fluctuation. That is, the control means operates the exhaust gas supply means such as a circulation blower based on a load request signal for the fuel cell sent from the load of the motor or the like, and controls the flow rate of the exhaust gas at the outlet of the gas flow path formed by the anode and the separator. Is 0.45m / s
The flow rate of the exhaust gas supplied to the anode is adjusted so as to have the above-described predetermined value.

When the load demand is reduced as described above, part of the exhaust gas discharged from the anode together with the anode reaction gas flowing out of the reformer is supplied to the anode again, so that it is supplied to the gas flow path of the anode. The gas is adjusted to have a hydrogen partial pressure corresponding to a low load requirement, and the gas flow rate is set to a sufficient value (0 to allow the drain to be conveyed toward the outlet even if drain is generated in the flow path). .45m /
s or more). Therefore, for example, even under the operating condition in which the hydrogen utilization rate is set to a high level, it is easily possible to sufficiently prevent the gas flow path on the anode side of the operating fuel cell from being blocked by the drain.

When the anode exhaust gas is mixed with the fuel gas and supplied to the anode, the total flow rate of the gas introduced into the anode and the exhaust gas discharged from the anode are compared with before the anode exhaust gas is supplied. The total gas flow increases. At this time, for example, if the discharge amount of the anode exhaust gas discharged to the outside of the apparatus is made to coincide with the supply amount of the anode exhaust gas mixed with the fuel gas, the hydrogen utilization rate at the anode is reduced even if the anode exhaust gas is supplied. It can be kept at the value before supply.

On the other hand, if the flow rate of the exhaust gas at the outlet of the gas flow path is less than 0.45 m / s, it becomes difficult to quickly discharge the gas from the outside of the gas flow path even if drain is generated in the gas flow path. The gas flow path is blocked by the drain.

Here, the control means in the fuel cell of the present invention sends a signal for activating the exhaust gas supply means when the load request falls to a preset lower limit. The "lower limit of the load requirement" means that the fuel cell device is operated under an operating condition in which the exhaust gas supply means is operated and a part of the exhaust gas discharged from the anode is not supplied to the anode via the exhaust gas supply line. In this case, the load required value is determined so that the flow rate of the exhaust gas at the outlet of the gas flow path formed by the anode and the separator takes a predetermined value of 0.45 m / s or more. The setting of the lower limit of the load requirement when operating the exhaust gas supply means is not particularly limited as long as the flow velocity of the exhaust gas at the outlet of the gas flow path is 0.45 m / s or more. Constitution,
It may be appropriately set depending on the use environment and the like, but is more preferably 0.6 m / s or more from the viewpoint of more reliably preventing the generation of drain.

When the load demand on the fuel cell falls below the lower limit of the load demand, the flow rate of the exhaust gas at the outlet of the gas flow path on the anode side after the operation of exhaust gas supply means such as a circulation blower is activated. The (predetermined value of 0.45 m / s or more) is not particularly limited as long as it is 0.45 m / s or more, and may be appropriately set depending on the output and configuration of the fuel cell device to be used, the use environment, and the like. From the viewpoint of more reliably preventing generation and even in the case where a drain is generated, the drain is more preferably discharged to the outside of the fuel cell at 0.6 m / s or more. Then, the flow rate of the exhaust gas at the outlet of the gas flow path on the anode side after operating the exhaust gas supply means such as a circulation blower is:
If it is 0.45 m / s or more, it may be set in advance so as to always take a constant value when the load request for the fuel cell falls below the lower limit of the load request described above, and fluctuates according to the load request. May be set in advance as follows.

For example, the lower limit of the load requirement and the flow rate of the exhaust gas at the outlet of the gas flow path on the anode side after the operation of the exhaust gas supply means such as a circulating blower are determined by the load of the fuel cell device used. It is possible to analyze and determine the correlation between the required value and the flow rate of the exhaust gas at the outlet of the gas flow channel based on theoretically calculated values and experimental values.

In this case, the exhaust gas supply means includes a circulating blower that sucks a part of the exhaust gas discharged from the anode into the exhaust gas supply line and discharges the exhaust gas toward a gas line connecting the reformer and the anode. And a flow rate adjusting means for adjusting the flow rate of the exhaust gas discharged from the circulation blower.

By using the circulation blower, even if there is a pressure difference between the exhaust gas discharged from the anode and the anode reactant gas flowing out of the reformer, both are surely mixed without any trouble and supplied to the anode. can do. Further, by using the flow rate adjusting means, the hydrogen partial pressure and the gas flow rate of the gas supplied to the anode can be adjusted more accurately and more quickly so as to correspond to the load demand.

Further, in the fuel cell device of the present invention,
It is provided on an exhaust gas line near the exhaust gas outlet of the anode, and further includes a first flow rate detecting means for detecting a flow rate of the exhaust gas. It is preferable to further control the exhaust gas supply means based on the above.

Since the number of gas channels formed in the separator on the anode side and the cross-sectional area thereof are predetermined, the flow rate of the exhaust gas from the anode is detected by the first flow rate detecting means, whereby the gas flow in the anode gas channel is determined. The flow rate at the outlet can be detected. That is, the flow rate at the outlet of the gas flow path of the anode can be directly detected by the first flow rate detecting means, and the flow rate at the outlet of the gas flow path of the anode can be directly determined per unit cell or per stack depending on the installation position. Can be easily detected. Therefore, with the above configuration, even when the flow velocity at the outlet of the gas flow path of the anode decreases due to a factor different from the fluctuation of the load demand on the fuel cell such as the usage environment of the fuel cell device, the gas flow path Can be sufficiently prevented from being blocked by the drain. The first flow rate detecting means may be provided, for example, for each fuel cell stack, or may be provided for each single cell constituting the stack as needed.

In this case, the fuel cell further includes a second flow rate detecting means for detecting a flow rate of the anode reaction gas flowing out of the reformer, wherein the control means determines a load request for the fuel cell and a detected value of the first flow rate detecting means. It is preferable to further control the exhaust gas supply means based on the detected value of the second flow rate detection means. With this configuration, the supply amount of the anode reaction gas flowing out of the reformer can be grasped more accurately, so that the supply amount of the exhaust gas to be supplied to the anode can be determined more accurately. Become. That is, the operating condition of the fuel cell can be changed more quickly with respect to the fluctuation of the load request, and the blockage of the anode gas flow channel by the drain can be more reliably prevented.

Further, in the fuel cell device of the present invention,
It is preferable that the apparatus further includes a droplet removing unit that is provided on the exhaust gas supply line near the inlet of the exhaust gas supply unit and removes droplets contained in the exhaust gas. Thereby, since the water vapor component in the exhaust gas supplied to the anode can be sufficiently removed, the generation of drain in the gas flow path of the anode can be effectively suppressed.

Further, the operating method of the fuel cell device according to the present invention comprises a fuel cell in which a plurality of unit cells each having a polymer electrolyte and a separator are disposed between an anode and a cathode, and a separator is provided. In the operating method of the fuel cell device, in which the generated anode reaction gas is supplied to the anode and the cathode reaction gas is supplied from the cathode reaction gas supply means to the cathode and power is generated by an electrochemical reaction, the operation is performed based on a load request for the fuel cell. A part of the exhaust gas discharged from the anode is taken out and supplied to the anode together with the anode reaction gas flowing out of the reformer, and the flow rate of the exhaust gas at the outlet of the gas flow path formed by the anode and the separator is 0.45 m / The flow rate of the exhaust gas supplied to the anode is adjusted so as to have a predetermined value of s or more.

In this case, it is preferable that the flow rate of the exhaust gas discharged from the anode is detected, and the flow rate of the exhaust gas supplied to the anode is adjusted based on the detected value.

Further, in this case, it is preferable to detect the flow rate of the anode reaction gas flowing out of the reformer and adjust the flow rate of the exhaust gas supplied to the anode based on the detected value.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a fuel cell device and a method of operating the fuel cell device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing a fuel cell device according to the present invention. The fuel cell device 1 shown in the figure is suitable for use as a power source for a mobile vehicle or a small cogeneration system, and includes a solid polymer electrolyte fuel cell FC. The fuel cell FC generates electric energy by an electrochemical reaction using a fuel gas containing hydrogen (anode reaction gas) and air (a cathode reaction gas) as an oxidizing gas. The electric energy generated by the fuel cell FC is used as a drive source for a moving vehicle or a power source for a small cogeneration system. The fuel cell device 1 may include a direct methanol fuel cell (DMFC).

As shown in FIG. 1, the fuel cell device 10
Plurality of polymer electrolyte fuel cells FC, fuel supply unit 12 for generating fuel gas, water supply unit 14, reformer 1
5 and a control device 90. Fuel supply unit 12
Has a fuel tank and a fuel pump (both not shown) for storing methanol or the like for generating fuel gas.
One end of a fuel line L8 is connected to the fuel supply unit 12. The fuel supply line L8 is provided with a flow control valve FR
V1 and the other end is connected to the reformer 15. The flow control valve FRV1 is electrically connected to the control device 90, and controls the opening time and closing time of the fuel line L8. As a result, the flow rate of methanol supplied from the fuel supply unit 12 to the reformer 15 is adjusted in accordance with the operation state of the fuel cell device 10.

Similarly, the water supply unit 14 has a water tank and a water pump (both not shown) for storing water used as a reforming fluid when reforming fuel (methanol). One end of a reforming water line L9 is connected to the water supply unit 14. The reforming water line L9 also has a flow control valve FRV2 on the way, and the other end is connected to the reformer 15. The flow control valve FRV2 is connected to the control device 9
0, and the opening time and closing time of the reforming water line L9 are controlled. As a result, the flow rate of the reforming water supplied from the water supply unit 14 to the reforming device 15 is adjusted according to the operation state of the fuel cell device 10.

The methanol supplied from the fuel supply unit 12 and the reforming water supplied from the water supply unit 14 are mixed and supplied to the reformer 15. The reformer 15 generates a fuel gas containing hydrogen by steam reforming using methanol supplied from the fuel supply unit 12 and reforming water supplied from the water supply unit 14. Therefore, the reformer 15 includes an evaporator 16, a reformer 17, and a selective oxidizer 18.

The process of generating the fuel gas in the reformer 15 will be described. The fuel supply unit 12 and the water supply unit 14
Is first supplied to the evaporating section 16. The evaporator 16 includes a burner (not shown).
The heat generated by the burner vaporizes and raises the temperature of the water-methanol mixed liquid to form a water-methanol mixed gas. And
The water-methanol mixed gas vaporized and heated in the evaporator 16 is
It flows into the reforming section 17.

Inside the reforming section 17, as a reforming catalyst,
For example, a honeycomb-shaped porous body (not shown) carrying a particulate catalyst is arranged. When the water-methanol mixed gas that has flowed into the reforming section 17 passes through the surface of the reforming catalyst, the reactions represented by the following equations (4) and (5) progress, and as a result, the hydrogen-rich reformed gas Is generated. Expressions (4) and (5) are expressed as expression (6). CH ₃ OH → CO + 2H ₂ -90.9 kJ / mol… (4) CO + H ₂ O → CO ₂ + H ₂ +41.0 kJ / mol… (5) CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ −49.8 kJ / mol… (6)

Since the steam reforming reaction represented by the above formulas (4) to (6) is an endothermic reaction, it is necessary to supply heat into the reforming section 17 to advance the reaction. To this end, it is preferable that the water / methanol mixed gas be configured to flow from the evaporator 16 into the reformer 17 while entraining heat. Further, a predetermined heating device may be provided in the reforming unit 17 so that heat for promoting the reaction is supplied from the heating device into the reforming unit 17. When the steam reforming reaction is caused to proceed by the Cu—Zn catalyst, the internal temperature of the reforming section 17 is preferably in a temperature range of 250 to 300 ° C.

Here, an air line (neither is shown) having a flow control valve in the middle thereof is connected to the reforming section 17.
A configuration may be adopted in which reforming air is supplied as needed. When the reforming air is supplied into the reforming unit 17, the reforming unit 17 performs a process between the methanol in the water-methanol mixed gas flowing from the evaporating unit 16 and the oxygen contained in the reforming air. The reaction represented by the following equation (7) proceeds. CH ₃ OH + ＯO ₂ → CO + H ₂ O + H ₂ +151.6 kJ / mol (7) Thereby, the heat due to the endothermic reaction can be further supplemented. And in this case, the flow control valve of the air line connected to the reforming unit 17 is also electrically connected to the control device 90,
It is preferable that the supply amount of air be controlled in accordance with the operating conditions of the fuel cell.

The reforming section 17 preferably includes a CO concentration measuring means such as a CO sensor or a temperature sensor for measuring the CO concentration in the reforming section 17. This makes it possible to monitor whether the steam reforming reaction in the reforming section 17 shown in (4) to (7) is proceeding in a predetermined steady state. And in this case, C
The O concentration measuring means is also electrically connected to the controller 90 to
The data in the reforming unit 17 measured by the O concentration measuring unit is output to the control device 90, and the supply amount of air into the reforming unit 17 is controlled based on the CO concentration in accordance with the operating condition of the fuel cell. It is preferable to have a configuration.

The reformed gas thus generated in the reforming section 17 flows into the selective oxidizing section 18 next. In the selective oxidation section 18, a porous body (not shown) supporting a CO selective oxidation catalyst such as a metallosilicate catalyst is arranged. An air line (not shown) having a flow control valve in the middle is connected to the selective oxidation unit 18.
The configuration is such that air for CO selective oxidation is supplied.
Then, the reformed gas flowing into the selective oxidation section 18 is
After passing through the surface of the selective oxidation catalyst, the supplied air for selective oxidation of CO is used, and the selective oxidation reaction represented by the following equation (8) proceeds. CO + 1 / 2O ₂ → CO ₂ +284.7 kJ / mol ... (8)

As a result, only the carbon monoxide in the reformed gas generated in the reforming section 17 is selectively oxidized, and the selective oxidizing section 18 generates fuel gas having a sufficiently reduced carbon monoxide concentration. Will be done. Then, the fuel gas generated in the selective oxidation section 18 of the reformer 15 is supplied to the fuel cell FC via the fuel gas supply line L1.

The selective oxidation portion 18 has an internal C
A CO concentration measuring means (not shown) such as a CO sensor or a temperature sensor for measuring the O concentration is provided.
It is configured to monitor whether or not the CO selective oxidation reaction in the selective oxidation section 18 shown in the equation (8) is proceeding in a predetermined steady state. Then, the CO concentration measuring means and C
The flow control valve for adjusting the flow rate of the O selective oxidation air is electrically connected to the control device 90, and the measured data of the CO concentration in the selective oxidation section 18 is output to the control device 90 and processed. In order to maintain the CO concentration in the selective oxidizing section 18 within an appropriate range, the supply amount of the CO selective oxidizing air is controlled according to the operating conditions of the fuel cell.

Further, a cooler 35 is disposed in the middle of the fuel gas supply line L1 connected to the outlet of the reformer 15. The temperature of the fuel gas flowing out of the reformer 15 and flowing through the fuel gas supply line L1 is increased in accordance with the reaction temperature of the steam reforming reaction that proceeds in the reformer 15, The battery is cooled to near the operating temperature of the battery FC.

Here, the cooler 35 is configured to be capable of separating condensed water and supplying the condensed water to the water supply unit 14 when the steam component condenses with cooling of the fuel gas. The control means 90 controls the supply amounts of fuel, water, reforming air, CO selective oxidizing air and the like to be supplied to the reforming device 15 so that the generated steam partial pressure of the fuel gas is reduced by the fuel cell FC. It may be adjusted in advance to a value equal to or lower than the saturated vapor pressure at the operating temperature. In this case, even if the fuel gas flowing out of the reformer 15 is cooled to the operating temperature of the fuel cell FC in the cooler 35, its water vapor component does not condense.

On the other hand, as shown in FIG. 1, the fuel cell device 10 comprises a blower B1 as a cathode reaction gas supply means for supplying air as a cathode reaction gas to the fuel cell FC.
Is provided. This blower B1 is provided with a flow control valve FRV
The fuel cell FC is connected to the fuel cell FC via an air supply line L2 having an air supply line 3, and sucks air in the atmosphere to increase the pressure to a predetermined pressure, and sends the pressure to the fuel cell FC. As a result, compressed air heated to a predetermined temperature (for example, about 120 ° C.) is supplied from the blower B1 to the fuel cell FC.

Further, a heat exchanger 70 is provided on an air supply line L2 connecting the blower B1 and the air inlet 47b connected to each cathode C of the fuel cell FC. As a result, the air pumped from the blower B1 flows into the air inlet 47b of the fuel cell FC after passing through the inside of the heat exchanger 70. The heat exchanger 70 is configured as a closed container, and has a heat transfer tube (not shown) disposed therein. And the cooling medium return line L5 of the cooling system 50 is connected to the fluid inlet of the heat transfer tube. Thereby, the stack 40 and the like are cooled to reflect a predetermined temperature (for example, 60 ° C. to 8
(About 0 ° C.) and the cooling medium outlet 4 of the fuel cell FC
A part of the cooling water or the like flowing out of 9b flows into the heat transfer tube arranged in the heat exchanger 70. A coolant return line L5 is connected again to the fluid outlet of the heat transfer tube arranged in the heat exchanger 70, and the coolant return line L5 is returned to the radiator R to be cooled and recirculated.

On the other hand, since a heat transfer tube through which cooling water or the like for cooling the fuel cell FC flows is disposed inside the heat exchanger 70, the air heated to a predetermined temperature (about 120 ° C.) Means that the fuel cell FC is cooled and heat exchange is performed via a heat transfer tube with a cooling medium heated to a predetermined temperature (for example, about 60 ° C. to 80 ° C.). Thereby, inside the heat exchanger 70, the air flowing from the blower B1 is close to the operating temperature of the fuel cell FC (for example, 60 ° C. to 80 ° C.).
Each cathode C of the fuel cell FC cooled to about
Will be supplied.

Here, when the polymer electrolyte membrane EM is humidified from the cathode C side, air is supplied to each cathode C together with a water vapor component by humidifying means (not shown). The temperature of the air flowing out of the heat exchanger 70 depends on the heat exchange conditions in the heat exchanger 70 and the like.
If the operating temperature is higher than the operating temperature of the heat exchanger 7,
If necessary, a cooling unit may be further provided on the air supply line L2 connecting the fuel cell FC with the fuel cell FC.

Further, the above-described reforming air is supplied to the selective oxidation section 1.
8 and an air line (not shown) for supplying the reforming air to the reforming unit 17 include an air supply line L2 connected to the blower B1.
It is good also as composition which branches from. This eliminates the need to separately provide a supply source for supplying the reforming air, so that the entire fuel cell device 10 can be made compact. Thus, the fuel cell FC receives the supply of the fuel gas from the reformer 15 and the supply of the air from the blower B1.

The fuel cell FC will be described in detail. As shown in FIG. 2, the fuel cell FC is a single cell UC.
There is a stack 40 in which a large number of (see FIG. 3) and separators SP (see FIGS. 3 and 4) are alternately stacked via a sealing material 21. Each single cell UC has an electrolyte membrane EM disposed between an anode A and a cathode C, which are gas diffusion electrodes. The stack 40 includes each single cell U
An anode current collector plate 41a connected to the anode A of C,
It is sandwiched between the cathode C of each unit cell UC and the cathode current collector 41b connected thereto. An insulating plate 42 is disposed outside the anode current collector 41a and the cathode current collector 41b.

Outside the insulating plates 42, flanges 44a and 44b are arranged via a stack tightening plate 43. The flanges 44a and 44b are connected by a membrane plate 45 and firmly fastened. Thus, the stack 40, the anode current collector 41a, the cathode current collector 41b, the insulating plate 42, and the like are integrated. Each of the flanges 44a and 44b is made of a solid material having a rib structure, thereby reducing the weight of the entire fuel cell FC.
Further, it is preferable to dispose an elastic body 46 such as a disc spring between the insulating plate 42 and the flanges 44a and 44b. it can.

Further, the fuel cell FC includes a cathode current collector 4
A fuel gas inlet 47a (anode reactant gas inlet) penetrates the upper left corner of the insulating plate 42 located on the side of 1b, and a fuel gas supply line L1 connected to the reformer 15 is connected to the fuel gas inlet 47a. Is done. Further, the fuel cell FC includes an insulating plate 4 located on the side of the cathode current collector 41b.
2 has an air inlet 47b (cathode reaction gas inlet) penetrating the upper right corner, and an air supply line L2 connected to the blower B is connected to the air inlet 47b. Thus, the fuel gas flows from the fuel gas inlet 47a to the anode A of each unit cell UC, and the air as the oxidizing gas flows from the air inlet 47b to the cathode C of each unit cell UC.

The electrolyte membrane EM is, for example, an ion exchange membrane formed of a solid polymer material such as a fluorine-containing polymer and exhibiting good ion conductivity in a wet state. As the solid polymer material constituting the polymer electrolyte membrane PEM, a perfluorocarbon polymer having a sulfonic acid group, a polysulfone resin, a perfluorocarbon polymer having a phosphonic acid group or a carboxylic acid group, or the like can be used. Examples of the product include Nafion (manufactured by DuPont) and the like.

On the other hand, the anode A and the cathode C, which are gas diffusion electrodes, each comprise a gas diffusion layer and a reaction layer (catalyst layer) formed on the gas diffusion layer. Here, the gas diffusion layer and the reaction layer will be briefly described. The gas diffusion layer smoothly and uniformly supplies the fuel gas or air supplied to each single cell UC to the reaction layer side, It plays a role in releasing electrons generated by the electrode reaction to the outside of the single cell UC. As a gas diffusion layer,
For example, a porous resin having electrical conductivity (in the present embodiment, carbon paper made of carbon fiber) is coated on a fluororesin (for example, PTFE [polytetrafluoroethylene]).
What has been subjected to a water-repellent treatment using is used.

The reaction layer plays the role of advancing the electrode reaction shown in the above-mentioned formula (1) for the anode A and the above-mentioned formula (2) for the cathode C. This reaction layer is a three-dimensional reaction site, that is, a three-phase interface area between a region composed of a catalyst and an ion-conductive electrolyte (electrolyte network) and a region supplied with fuel gas or air (gas diffusion network). Is being increased. Specifically, by forming a basic skeleton with catalyst-supporting carbon black fine particles having a large catalyst surface area, and dispersing a water repellent such as PTFE to a part of the skeleton to perform a water repellent treatment, the hydrophobicity is improved. Build a gas diffusion network. Then, a solution in which a polymer electrolyte is dissolved in an organic solvent is applied to the other portion of the skeleton by, for example, permeation coating, and the surface of the catalyst-carrying carbon black is coated with the polymer electrolyte to construct a hydrophilic electrolyte network. This makes it possible to efficiently contact the fuel gas or air, the ions (protons), and the catalyst, and to promptly advance the respective electrode reactions.

The anode A and the cathode C comprising such a gas diffusion layer and a reaction layer are manufactured, for example, according to the following procedure. First, hydrophilic carbon black fine particles, hydrophobic carbon black fine particles, and PTFE are mixed in an organic solvent containing a surfactant, and dispersed and mixed with a USHM (ultrasonic homogenizer) or a bead mill to form a paste slurry. Prepare. Next, the slurry is applied on a carbon paper serving as a gas diffusion layer so as to have a uniform thickness, and then dried. Then, the carbon paper is subjected to a heat treatment using an electric furnace or a hot press to sinter the PTFE in the slurry and remove the surfactant to form a reaction layer.
Further, a solution containing a metal salt constituting an electrode catalyst (for example, an aqueous solution of chloroplatinic acid) is applied to the surface of the reaction layer, dried and thermally decomposed in an electric furnace or the like, and then subjected to a treatment such as hydrogen reduction.
Thus, the anode A and the cathode C are completed.

In this case, since the solution containing the metal salt constituting the electrode catalyst penetrates into the details in the reaction layer via the hydrophilic electrolyte network, the reaction after the hydrogen reduction treatment or the like is performed. The electrode catalyst is supported in the layer with a high degree of dispersion. If necessary, in order to reduce the amount of supported catalyst or to construct a more hydrophobic gas diffusion network, unsupported carbon black fine particles previously coated with a fluororesin are used as catalyst-supporting carbon black particles. It may be dispersed in black fine particles.

Further, in order to reduce the electric resistance of the reaction layer, the skeleton composed of the catalyst-free carbon black fine particles is coated with only the polymer electrolyte without subjecting the skeleton to water repellency treatment, so that the polymer electrolyte itself has a structure. It is also possible to use the hydrophobic region that is physically present as a gas diffusion network. Furthermore, the anode A and the cathode C may be configured using carbon felt, carbon cloth made of carbon fiber, or the like.

The anode A having the above-described configuration
And the cathode C as an electrolyte membrane E made of a solid polymer material
By joining to M, a single cell UC is formed.
Specifically, a single cell UC is completed by bringing a reaction layer of the anode A and the cathode C into contact with the electrolyte membrane EM and performing a heat treatment with an electric furnace, a hot press or the like. In this case, in order to improve the adhesion at the joining surface between the anode A and the cathode C, a small amount of a solution obtained by dissolving a polymer electrolyte membrane in an organic solvent is applied to the surface of the reaction layer of the anode A and the cathode C, and then heat-treated. Is preferably applied. Further, before joining the anode A and the cathode C, the impurities in the electrolyte membrane EM are oxidized and removed with a dilute solution of hydrogen peroxide, and then the ion exchange groups in the electrolyte membrane EM are converted to proton foam with a sulfuric acid aqueous solution. It is preferable to perform an activation treatment of the electrolyte membrane, for example.

As shown in FIG. 3, together with the single cell UC configured as described above, the separator SP forming the stack 40 is arranged such that the single cell UC is connected to the anode A side and the cathode C side with respect to one single cell UC. Are mounted one by one. The separator SP is formed of, for example, a gas-impermeable conductive member such as dense carbon that has been made gas-impermeable by compressing carbon, and has a rectangular shape as shown in FIGS. 4 (a) and 4 (b). It has a thin plate shape. Here, FIG.
Is a plan view of a surface (hereinafter, referred to as an “anode contact surface”) of the front and back surfaces of the separator SP viewed from the anode A side, and a surface (hereinafter, referred to as a “cathode contact surface”) contacting the cathode C. FIG. 2 is a plan view of the surface (referred to as “surface”) viewed from the cathode C side.

As shown in FIGS. 4A and 4B,
Slot-shaped openings 50a, 50b, 51a, 51b extending along the side edges are formed at the four corners of the separator SP. The anode contact surface of the separator SP has a plurality of grooves 52 bent in an S-shape such that one end communicates with the upper right opening 50a in the figure and the other end communicates with the lower left opening 51a in the figure. Is formed. Further, one end of the cathode contact surface of the separator SP communicates with the upper right opening 50b in the figure, and the other end thereof communicates with the lower left opening 51b in the figure.
A plurality of grooves 53 that bend in an S-shape are formed so as to communicate with.

When the stack 40 is formed by laminating a large number of the separators SP and the single cells UC configured as described above, each of the openings 50a, 50b, 51a, and 51b forms one flow path. Further, each groove 52 formed on the anode contact surface of each separator SP is provided with each single cell UC.
The fuel gas flow path 54 is defined by the surface of the anode A (see FIG. 3). Further, each groove 53 formed on the cathode contact surface of each separator SP defines an air flow path 55 with the surface of the cathode C of each single cell UC (see FIG. 3). The flow path formed by the opening 50a communicates with the fuel gas inlet 47a, and the flow path formed by the opening 50b communicates with the air inlet 47b.

As a result, the fuel gas generated by the reformer 15 is supplied to each groove 52 of each separator SP through the fuel gas inlet 47a and the opening 50a of each separator SP.
And flows into the fuel gas flow passage 54 defined by the anode A surface. Then, the fuel gas is supplied to the fuel gas passage 54.
, The reaction represented by the above formula (1) proceeds at each anode A. Further, the air supplied from the blower B as the oxidizing gas is supplied to the air inlet 47b and the respective separators SP.
Flows into the air flow path 55 defined by the grooves 53 of the separators SP and the surface of the cathode C via the flow path formed by the opening 50b. When the air flows through the air flow path 55, the reaction represented by the above formula (2) proceeds at each cathode C. As a result, in each single cell UC, the above (3)
The whole cell reaction shown in the equation proceeds, and an electromotive force can be obtained from the anode current collector 41a and the cathode current collector 41b of the fuel cell FC.

The separator SP of the fuel cell FC
Here, the groove 52 defining the fuel gas flow path 54 and the groove 53 defining the air flow path 55 are bent in an S-shape. Therefore, the fuel gas supplied to the anode A of each single cell UC regularly proceeds in the S-shaped fuel gas flow path 54 from the opening 50a toward the opening 51a.
At the anode reaction site on the way. Similarly, the air supplied to the cathode C of each single cell UC travels regularly through the S-shaped air flow path 55 from the opening 50b to the opening 51b. Consumed at the reaction site.

As a result, the fuel gas and the air proceed in the opposite directions and regularly, so that the reaction heat accompanying the progress of the electrode reaction may cause an uneven temperature distribution in each of the anodes A and the cathodes C. It can be suppressed effectively. As a result, in the fuel cell FC, the anode electrode reaction shown in (1) and the cathode electrode reaction shown in (2) proceed favorably. Note that the fuel gas flow path 54 and the air flow path 55 are not limited to the S-shape, and the flow path 5 of another form may be used.
Grooves 52, 53 may be formed in cathode C to define 4,55.

The fuel gas reacted at the anode A while flowing through the fuel gas flow path 54 becomes anode exhaust gas and flows into the flow path formed by the opening 51a of each separator SP. The flow path formed by the opening 51a of each separator SP is connected to an anode exhaust gas outlet 48a (see FIG. 2) disposed below the air inlet 47b. The air that has reacted at the cathode C while flowing through the air passage 55 is
It becomes the cathode exhaust gas and the opening 51 of each separator SP
b flows into the channel formed. The flow path formed by the opening 51b of each separator SP is connected to a cathode exhaust gas outlet 48b (see FIG. 2) disposed below the fuel gas inlet 47a.

Anode exhaust gas outlet 48a of fuel cell FC
Is connected to the evaporator 16 of the reformer 15 via the anode exhaust gas line L3 as shown in FIG. Similarly, the cathode exhaust gas outlet 48b of the fuel cell FC is also connected to the evaporator 16 (burner) of the reformer 15 via the cathode exhaust gas line L4. And the fuel cell F
The anode exhaust gas generated at each anode A of C is reused as fuel by a burner provided in the evaporator 16 of the reformer 15, and the cathode exhaust gas generated at each cathode C is reused as an oxidant.

A pressure regulating valve (not shown) may be arranged in the middle of the anode exhaust gas line L3 and a pressure regulating valve may be arranged in the middle of the cathode exhaust gas line L4. With these pressure regulating valves, the pressure of the anode exhaust gas flowing through the anode exhaust gas line L3 can be maintained at a predetermined value at the outlet of the fuel cell FC, and the pressure of the cathode exhaust gas flowing through the cathode exhaust gas line L4 can be maintained at the outlet of the fuel cell FC. Can be maintained at a predetermined value. Thereby, the fuel cell FC
, The fluid pressure in the inside of each separator SP
It is possible to keep the pressure of the fuel gas and the air inside the flow paths formed by the openings 50a, 50b, 51a, 51b, the fuel gas flow paths 54, and the air flow paths 55 constant. The battery FC can be operated at a desired battery voltage.

Here, as shown in FIG. 1, the fuel cell device 10 will be described below in view of sufficiently preventing the gas flow path on the anode A side of the operating fuel cell FC from being blocked by the drain. An exhaust gas supply line L7, a circulation blower B2, a flow control valve FRV4, and a control unit 90 are provided. Further, in this fuel cell device 10,
A flow rate detector (first flow rate detecting means) S1 for measuring the total flow rate of the anode exhaust gas flowing out from the anodes A of the plurality of fuel cells FC is provided on an anode exhaust gas line L3 connecting the fuel cell FC and the reformer 15. Is provided. Also,
In the fuel cell device 10, a flow rate detector (second flow rate detecting means) S2 for measuring the flow rate of the fuel gas flowing out of the cooler 35 is provided with a fuel gas supply line L1 connecting the cooler 35 and the fuel cell FC. It is provided above.

The exhaust gas supply line L7 is a gas line for supplying a part of the anode exhaust gas flowing out from the anodes A of the fuel cells FC to the anodes A of the fuel cells FC again. The exhaust gas supply line L7 has one end connected to an anode exhaust gas line L3 connecting the flow detector S1 and the evaporator 16 of the reformer 15, and the other end connecting a fuel gas connecting the flow detector S2 and the fuel cell FC. It is connected to the supply line L1. And the exhaust gas supply line L7
In the middle, a part of the exhaust gas discharged from the anode A of the fuel cell FC is sucked into the exhaust gas supply line L7,
A circulating blower B2 that discharges toward the junction of the fuel gas supply line L1 and the exhaust gas supply line L7, and a flow control valve FRV4 that functions as a flow control unit that controls the flow rate of the exhaust gas discharged from the circulating blower are provided. ing.

The flow rate detector S1 and the flow rate detector S
2. The circulation blower B2 and the flow control valve FRV4 are electrically connected to the control device 90. As described above, the circulation blower B2 and the flow rate regulating valve FRV4 are connected to the load request value (current value and the like) for the fuel cell and the flow rate detector S1.
Is controlled by the control means 90 based on the detection value at the flow rate detector S2 and the detection value at the flow rate detector S2. In this way, during the operation of the fuel cell FC, when the load demand on the fuel cell decreases and reaches the set lower limit, the flow rate of the exhaust gas at each outlet of each fuel gas passage 54 formed in the anode A Is adjusted to be a predetermined value of 0.45 m / s or more. As a result, during the operation of the fuel cell device 10, the load demand on the fuel cell FC decreases, and each fuel gas flow path 54
Even if a drain is generated in the fuel cell, the drain can be quickly discharged to the outside, so that the fuel cell FC can always be operated in a stable state according to the load fluctuation.

The control device 90 mainly includes the flow control valve FR
V1 to FRV4 and the circulation blower B2 are controlled to adjust the flow rates of methanol, reforming water, and air supplied to the reformer 15 to predetermined values, and an anode reaction gas (fuel gas) supplied to the fuel cell FC. ), The flow rates of air and anode exhaust gas are adjusted to predetermined values.

As shown in FIG. 5, the control device 90
It has a CPU 91, a ROM 92, and a RAM 93.
The CPU 91 includes a microprocessor or the like, and performs various arithmetic processing. A program for control / arithmetic processing is stored in the ROM 92 in advance.
Is used to read and write various data during control / arithmetic processing.

The control device 90 has an input / output port 94 connected to the CPU 91, as shown in FIG. The input / output port 94 has a flow control valve FRV1.
FRV4, blower B1, circulation blower B2, pump Pc
(Not shown) and a radiator R (not shown). Therefore, the blower B1, the circulation blower B2, the pump Pc, and the radiator R are connected via the input / output port 94.
Various signals and the like generated by the arithmetic processing of the CPU 91 are provided.

Further, a flow rate detector S1 and a flow rate detector S2 are connected to the input / output port 94 of the controller 90. Then, detection signals generated by the flow rate detectors S1 and S2 are given to the CPU 91. Also,
An input / output port 94 of the control device 90 has a fuel cell F
Load setting means (not shown) for setting a load on C is further connected, and a load request signal generated by the load request means is given to the CPU 91.

In addition, the control device 90 has a storage device 95, which is connected to the CPU 91 via an input / output port 94. In this storage device 95,
Based on the load request signal and the detection signals generated by the flow detectors S1 and S2, the flow control valve FRV
1 to FRV4, blower B1, circulation blower B2, pump P
c, data for controlling the radiator R is stored.

That is, the storage device 95 stores the fuel cell F
A table indicating the flow rate of the flow control valve FRV1 according to the load request for C, and the flow control valves FRV2 to FRV
4 and data indicating a predetermined proportionality constant determined for 4. Further, when the load request for the fuel cell FC decreases to a preset lower limit, the fuel cell F
A circulation blower such that the flow rate of the anode reaction gas at each outlet of each fuel gas flow path 54 formed by the anode A of the single cell UC and the separator SP constituting the stack of C is 0.45 or more. B2 and flow control valve FR
Data for controlling V4 is also stored. These various data are read out by the CPU 91 which has received the flow rate detection signal and the load request signal of each section. Then, based on the temperature detection signal and the load request signal of each section, the CPU 91 controls the flow rate regulating valves FRV1 to FRV4, the blower B1, the circulation blower B2, the pump Pc, the radiator R
Generate a control signal to send to control.

When the load request for the fuel cell FC has decreased to a preset lower limit, or when the anode A converted from the total flow rate of the anode exhaust gas of the fuel cell FC due to other factors other than the decrease in the load request. And separator SP
When the flow rate of the exhaust gas at each outlet of each fuel gas flow path 54 formed by the above becomes a value less than 0.45 m / s,
The data for controlling the circulation blower B2 and the flow regulating valve FRV4 includes the scale, output,
It is appropriately determined according to the operating conditions of the fuel cell (for example, operating temperature, reaction pressure of anode reaction gas, reaction pressure of cathode reaction gas, set hydrogen utilization rate, set so-called S / C ratio range, etc.) and the like. Are the theoretically calculated values,
It can be determined based on experimental values and the like.

Further, a table indicating the flow rate at the flow rate regulating valve FRV1 according to the load request to the fuel cell FC, that is, the table showing the supply amount of methanol according to the load request, is similarly determined based on theoretically calculated values, experimental values, and the like. be able to. Further, the proportionality constants related to the flow control valves FRV2 to FRV4 are the supply amount of methanol determined by the flow rate at the flow control valve FRV1, the supply amount of reforming water, the supply amount of air for reforming reaction, and the air for CO selective oxidation. From each of the flow control valves FRV2 to FRV4. Instead of storing such proportional constant data in the storage device 95, data indicating a flow rate according to a load request to the fuel cell FC is created for each of the flow rate adjustment valves FRV1 to FRV4, and these data are stored. The information may be stored in the device 95.

With the control device 90 configured as described above, the flow regulating valves FRV1 to FRV4, the blower B1, the circulation blower B2, the pump Pc, and the radiator R are controlled reliably and accurately. Therefore, the fuel line L8, the reforming water line L9, the air supply line L2, the fuel gas supply line L1, and the exhaust gas supply line L7 supply fuel methanol, reforming water, air as a cathode reaction gas,
Fuel gas having a predetermined temperature and component composition and anode exhaust gas are stably and accurately supplied to each target device. Note that the control device 90 can be configured as a sequencer.

As described above, the CO concentration detecting means, the air supply means for supplying air for partial oxidation, and the air for selective oxidation are supplied to the reforming section 17 and the selective oxidizing section 18 of the reformer 15. In the case where air supply means for supplying air are provided as necessary, they are also connected to the control device 90, and based on a detection signal obtained from the CO concentration detection means, the reforming section 17 and the selective oxidizing section of the reforming apparatus 15 are provided. Each reaction in 18 may be controlled according to the load fluctuation. Thereby, from the reformer 15,
The fuel gas in which the CO partial pressure and the water vapor partial pressure are precisely adjusted to predetermined values is supplied to the anode A.

The so-called S / C ratio, which is one of the operating conditions for operating the fuel cell 10 of the present invention, that is, the ratio of the supply amount of reforming water (mol) / the supply amount of methanol (mol) The range of the ratio is set as follows. That is, the S / C ratio is a predetermined value of the reaction temperature of the reforming unit 17, the reaction temperature of the selective oxidizing unit 18, the temperature of the fuel gas flowing out of the reformer 15, and the operating temperature of the fuel cell FC. Then, the rate constants of the reforming reaction and the selective oxidation reaction represented by the equations (4) to (8) are set respectively, and methanol, reforming water, the reforming unit 17 and the selective oxidizing unit 18 are set. This is set by performing a kinetic analysis by changing the amount of air supplied to the fuel cell and calculating the component composition of the fuel gas flowing out of the reformer 15. At this time,
For example, taking into account the condition of the variation range of the load requirement value for the fuel cell and the condition of the variation range of the humidification condition of the polymer electrolyte membrane of the fuel cell, the result of the component composition in the fuel gas calculated and the Partial pressure of hydrogen in fuel gas flowing out of
The S / C ratio is determined so that the CO partial pressure, the water vapor pressure, and the like satisfy these conditions. In addition, as a reaction of the reforming unit 17,
Similarly, when the partial oxidation reaction of fuel such as methanol as shown in the equation (7) is not performed, the S / S in the case where a desired steam pressure in the fuel gas flowing out of the reformer 15 is obtained.
Find the C ratio.

For example, when the operating pressure of the fuel cell FC is 1.6ata
(98066 Pa), the operating temperature of the fuel cell FC is 80 ° C., the reaction temperature of the reforming section 17 and the selective oxidizing section 1
8 is a predetermined temperature and the temperature T1 of the fuel gas flowing out of the reformer 15 is 120 to 200 ° C., the flow control valves FRV1 and FRV2 are controlled to control the reforming water The ratio (S / C ratio) of the supply amount (mol) of methanol / the supply amount (mol) of methanol is preferably 1.5 to 2.5, more preferably 1.8 to 2.0.

Here, if the S / C ratio is less than 1.5, the concentration of CO in the fuel gas flowing out of the reformer 15 increases, and the electrode catalyst is covered in each anode A of the fuel cell FC. The tendency for the poison to progress significantly increases. On the other hand, when the S / C ratio exceeds 2.5, it becomes necessary to evaporate a large amount of water, which causes a problem of lowering system efficiency. In some cases, the cooling condition of the selective oxidizing unit 18 may be changed to reduce the CO concentration as necessary, and the reaction temperature of the selective oxidizing unit 18 may be lower than usual. Then, if necessary, the supply amount of air supplied to the reforming unit 17 and the selective oxidizing unit 18 is controlled so that the reformer 15 (7) and / or
Alternatively, the reaction proceeds by supplying a predetermined amount of air based on the stoichiometric ratio represented by the formula (8).

On the other hand, the fuel cell FC thus configured
Generates heat as the anode electrode reaction shown in the above (1) and the cathode electrode reaction shown in the above (2) progress. However, in order to stabilize the operation of the fuel cell FC, the operating temperature is kept substantially constant. It is important to. For this reason, the fuel cell FC is configured to allow a cooling medium to flow therein, and the fuel cell device 10 is provided with a cooling system 50. The cooling structure of the fuel cell FC will be described. As shown in FIGS. 4A and 4B, each separator SP forming the stack 40 of the fuel cell FC includes an opening 50a and an opening 51b. An additional opening 56 is formed therebetween. Further, an opening 57 is formed between the opening 50b and the opening 51a so as to face the opening 56.

The openings 56 and 57 of each separator SP thus formed form one flow path when the stack 40 is formed by laminating many separators SP and single cells UC. . The flow path formed by each opening 56 and the flow path formed by each opening 57 are flow paths (not shown) formed inside the flange 44a disposed on the anode current collector 41a side. And a cooling channel 58 (see FIG. 1). Further, as shown in FIG. 2, the flange 44b of the fuel cell FC
A cooling medium inlet 49a is provided on the side, and the cooling medium inlet 49a communicates with a flow path formed by each of the openings 56. Further, the flange 44 of the fuel cell FC
A cooling medium outlet 49b is provided on the b side, and the cooling medium outlet 49b communicates with a flow path formed by each of the openings 57.

On the other hand, the cooling system 50 includes a cooling medium circulation pump Pc, a cooling medium line L6, a cooling medium return line L
5. The radiator R is composed of a heat exchanger and a fan. That is, as shown in FIG. 1, the cooling medium circulation pump Pc is connected to the cooling medium inlet 49a of the fuel cell FC via the cooling medium line L6. Further, a cooling medium return line L5 is connected to a cooling medium outlet 49b of the fuel cell FC, and the cooling medium return line L5 is connected to a refrigerant inlet of a heat exchanger constituting the radiator R.

Therefore, when the cooling medium circulation pump Pc is operated, the cooling water and the like are introduced into the cooling flow path 58 of the fuel cell FC through the cooling medium line L6 and the cooling medium inlet 49a, and the fuel cell FC is stacked. The cooling water or the like that has been heated by depriving the heat from the cooling medium 40 and the like is returned to the radiator R via the cooling medium outlet 49b and the cooling medium return line L5. The cooling water or the like is cooled by the radiator R, and the cooling medium circulation pump Pc
Is supplied to the fuel cell FC again. Thereby, the operating temperature of the fuel cell FC is always kept in a suitable range (for example, about 60 ° C. to 80 ° C.).

[0093] Here, in the fuel cell FC, a predetermined portion of the temperature sensor S _FC (not shown) of each stack 40 to measure the temperature T _FC of the fuel cell FC in operation, or if necessary Each single cell U constituting each stack 40
You may prepare for every C. And in this case, connects the temperature sensor S _FC and the radiator R controller 90 electrically, and outputs to the temperature T _FC controller data 90 in the temperature sensor S _FC fuel cell measured by FC And controlling the output of the radiator R to adjust the operating temperature of the fuel cell FC.

The cooling water or the like flowing through the cooling system 50 may be used as a cold heat source for cooling the fuel gas by the cooler 35. Further, the cooling water or the like flowing through the cooling system 50 may be used as a cold source for adjusting the inside of the reforming unit 17 and the selective oxidizing unit 18 of the reformer 15 to a predetermined reaction temperature.

Next, the operation of the above-described fuel cell device 10 will be described with reference to the flowchart shown in FIG.

When starting the fuel cell device 10, the CPU 91 of the control device 90 outputs a drive signal to the pump Pc to start circulation of the cooling water. Next, after igniting the burner of the evaporating section 16 of the reformer 15, the CPU 91 outputs a drive signal to the flow rate adjusting valves FRV1 to FRV3 and air supply means for the reformer 15 arranged as necessary. , Methanol, reforming water, reforming air, CO selective oxidizing air, etc., are supplied to the reformer 15 under predetermined conditions.
The reaction at 5 is started. Next, the reaction temperature of each part of the reformer 15 reaches a predetermined temperature, and the component composition (hydrogen partial pressure, CO partial pressure, water vapor partial pressure, etc.) of the fuel gas flowing out of the reformer 15 changes according to the fuel cell. CPU 91 sends a control signal for supplying the fuel gas FC flowing out of the reformer 15 to the fuel cell FC after reaching a state in which it can fluctuate in response to a change in the load request for the blower B1 and the radiator R. To start the reaction of the fuel cell FC. In addition, for example, a bypass line (not shown in FIG. 1) is branched from the fuel gas supply line L1, and the reformer 1
5 can be switched between the fuel gas supply line L1 and the bypass line.
Until the reaction temperature of each section of the reformer 15 reaches a predetermined temperature, the fuel gas flowing out of the reformer 15 through the bypass line is controlled to be guided to the outside or the burner of the evaporator 16 (S10).

When the reformer 15 reaches the steady operating state and the fuel gas is supplied to the anode A, CP
U91, based on data for steadily operating the entire fuel cell device in response to a load request, as described below, transmits new drive signals to the flow control valves FRV1 to FRV.
4. Transmission to the pump Pc, the blower B1, the circulation blower B2, the radiator R, and the like, to start balanced control of the entire fuel cell device 10. At this time, as described above,
Since the fuel cell FC and the cooler 35 are adjusted to a predetermined operation temperature, even when the supply of the fuel gas and the air starts to be started, the fuel cell FC and the cooler 35 can quickly and steadily operate at a predetermined output. The operating reformer 15, the cooler 35, and the fuel cell FC
Of the radiator R and the pump P, for example, based on the detection results of the temperature sensors provided for them.
By controlling the driving states such as 3 by the control device 90, it is possible to maintain the temperature within a desired temperature range.

In this way, when the fuel cell device 10 starts operating steadily under the predetermined operating conditions, a load request signal is given to the CPU 91 of the control device 90 from the predetermined load setting means. The CPU 91 also transmits a detection signal indicating the total flow rate of the anode exhaust gas of the fuel cell FC transmitted from the flow rate detector S1 and a detection signal indicating the flow rate of the fuel gas flowing out of the reformer 15 transmitted from the flow rate detector S2. And a signal (S20).

Next, the CPU 91 compares the load request value indicated by the received load request signal with the set lower limit value of the load request stored in the storage device 95. Also, the CPU 91
Compares the total anode exhaust gas flow rate indicated by the received detection signal from the flow rate detector S1 with the set lower limit flow rate of the total anode exhaust gas flow stored in the storage device 95. Further, the CPU 91 compares the fuel gas flow rate indicated by the received detection signal from the flow rate detector S2 with the set lower limit flow rate of the fuel gas flow rate stored in the storage device 95 (S3).
0).

The load request value indicated by the received load request signal exceeds the set lower limit value, the total flow rate of the received anode exhaust gas exceeds the set lower limit flow rate, and When the flow rate exceeds the set lower limit flow rate, the CPU 91 accesses a table indicating the flow rate at the flow rate adjustment valve FRV1 stored in the storage device 95 based on the load request signal.
Then, the CPU 91 reads data corresponding to the load request for the fuel cell FC indicated by the load request signal from the table, and based on the data indicating the flow rate at the flow rate regulating valve FRV1 corresponding to the load request. Thus, a control signal to be sent to the flow control valve FRV1 is generated. Thus, by determining the flow rate in the flow rate regulating valve FRV1, the supply amount of methanol according to the load request for the fuel cell FC is determined (S4).
0).

In step S40, the amount of methanol supplied according to the load request for the fuel cell FC is determined.
The PU 91 then reads the flow control valve FR from the storage device 95.
Data indicating a predetermined proportionality constant determined for V2 and the flow control valve FRV3 is read. And the CPU 91
Generates a control signal to be sent to the flow control valves FRV2 and FRV3 by multiplying the data by the data indicating the flow rate in the flow control valve FRV1 corresponding to the load request read in S40. Thereby, the flow control valve FRV
The supply amount of the reforming water supplied via the second control valve 2 and the supply amount of the air supplied via the flow control valve FRV3 are determined in accordance with the load request for the fuel cell FC. At this time, in a case where air is supplied to the reforming unit 17 and the selective oxidizing unit 18 of the reforming device 15, respectively, the air supply means is also the same as the above-mentioned flow regulating valves FRV2 and FRV3. The proportional control may be performed on the flow rate adjustment valve FRV1. (S50).

The CP that has performed the processing in S40 and S50
U91 is provided with each of the flow control valves FRV1 to FRV according to the load request.
A control signal indicating the flow rate for each of the RVs 3 is transmitted (S60).

Then, the actuators of the flow control valves FRV1 to FRV3, which have received the control signal generated by the CPU 91 in S60 from the controller 90,
When the control signal is received from No. 1, the opening degree is changed to meet the load request. As a result, the amount of methanol and the reforming water according to the load demand are optimally and accurately supplied to the evaporator 16 of the reformer 15, and the reformer 17 and the selective oxidizer 18 are supplied with the load demand. An appropriate amount of reforming air is supplied optimally and accurately. Therefore, even if the load demand on the fuel cell FC changes and the amount of fuel gas to be supplied to the fuel cell FC changes, the reformer 15 can always generate the fuel gas having an extremely low carbon monoxide concentration. .
Further, by supplying a fuel gas having a very low carbon monoxide concentration to the fuel cell FC with high accuracy, the fuel cell FC can be operated stably and the life of the anode A can be prolonged. Further, an amount of air corresponding to the load request is accurately supplied to the air inlet 47b through the heat exchanger 70.

The processes in S10 to S60 described above are controlled as long as all of the conditions of the load request, the anode exhaust gas flow rate, and the fuel gas flow rate in S30 are maintained at the set lower limit values and the set lower limit flow rates, respectively. It is repeated each time the CPU 91 of the device 90 receives the load request signal.

On the other hand, in S30, when at least one of the conditions of the load request, the anode exhaust gas flow rate, and the fuel gas flow rate matches the set lower limit value and the set lower limit flow rate, the CPU 1 executes the fuel cell operation. Even if drains are generated in the fuel gas flow paths 54 of the anode A due to a decrease in load demand on the fuel cell during operation of the apparatus, the drains are immediately discharged from the fuel gas flow paths 54 to the outside. Flow control valves FRV1 to FRV
3. In addition to the blower B1, the radiator R, etc., the flow control valve FRV4 and the circulation blower B2 are operated, and the control thereof is started.

That is, first, the CPU 91 accesses a table indicating the flow rate in the flow rate regulating valve FRV1 stored in the storage device 95 based on the load request signal in S30. Then, the CPU 91 reads the fuel cell FC indicated in the load request signal from the table.
And reads out data corresponding to the load request, and generates a control signal to be sent to the flow control valve FRV1 based on data indicating the flow rate at the flow control valve FRV1 corresponding to the load request. Thus, by determining the flow rate in the flow rate regulating valve FRV1, the supply amount of methanol according to the load request for the fuel cell FC is determined in the same manner as in S40 (S70).

Further, in S70, the amount of methanol supplied in accordance with the load request for the fuel cell FC is determined.
Next, U91 reads the flow control valve FRV from the storage device 95.
2 and data indicating a predetermined proportionality constant determined for the flow control valve FRV3. This data is
For example, it may be the same as the data in S50. Then, the CPU 91 multiplies the data by the data indicating the flow rate at the flow control valve FRV1 corresponding to the load request read at S40, and multiplies the flow control valve FRV2 and the flow control valve F.
Generate a control signal to be sent to RV3. As a result, the supply amounts of the reforming water supplied through the flow control valve FRV2 and the air supplied through the flow control valve FRV3 are determined in accordance with the load request for the fuel cell FC. At this time, the reforming section 17 of the reformer 15
In the case of supplying air to the selective oxidation unit 18 and the air supply means, the air supply means may be proportionally controlled with respect to the flow control valve FRV1, similarly to the flow control valves FRV2 and FRV3. (S80).

Next, the CPU 91 reads from the storage device 95
The flow rate of the exhaust gas at each outlet of each fuel gas passage 54 formed by the anode A and the separator SP is 0.45
Predetermined data determined for the flow rate regulating valve FRV4 based on the required load value, the total flow rate of the anode exhaust gas, or the flow rate of the fuel gas is read so as to be a predetermined value of m / s or more. Then, the CPU 91 generates a control signal for sending the flow rate adjustment valve FRV4 based on the data. Thus, the supply amount of the anode exhaust gas supplied via the flow control valve FRV4 is determined so as to comply with the load request for the fuel cell FC (S90).

Next, the CPU 91 sends a drive signal to the circulation blower B2 and the flow control valve FRV4 (S100).
Next, the CPU 9 that has performed the processing in S70 to S100
1 is a flow control valve FRV1 to FRV corresponding to a load request.
A control signal indicating the flow rate for each of No. 4 is transmitted (S110).

The actuators of the flow control valves FRV1 to FRV4, which have received the control signals generated by the CPU 91 in S70 to S90 from the control device 90,
When the control signal is received from the CPU 91, the opening degree is changed so as to respond to the load request. As a result, the amount of methanol and the reforming water according to the load demand are optimally and accurately supplied to the evaporating section 16 of the reforming unit 15, and
An amount of reforming air corresponding to the load demand is optimally and accurately supplied to the selective oxidation section 7 and the selective oxidation section 18. Further, the reformer 1
The mixed gas of the fuel gas supplied to the anode A from the fuel gas 5 and the anode exhaust gas supplied to the anode A from the exhaust gas supply line, The flow rate is controlled so that the flow rate becomes a predetermined value of 0.45 m / s or more.

When the anode exhaust gas is mixed with the fuel gas and supplied to the anode A as described above, the total flow rate of the gas introduced into the anode A and the flow rate from the anode A are higher than before the anode exhaust gas is supplied. The total flow of the exhausted gas increases. At this time, for example, if the discharge amount of the anode exhaust gas discharged to the outside of the apparatus is made to coincide with the supply amount of the anode exhaust gas mixed with the fuel gas, the hydrogen utilization rate at the anode A can be reduced even if the anode exhaust gas is supplied. Can be kept at the value before supplying.

Therefore, even if the load demand on the fuel cell FC changes during the operation of the fuel cell device and a drain is generated at each outlet of each fuel gas flow passage 54 of the anode A, the drain is immediately discharged to the respective outlet. Since the fuel gas can be discharged from the fuel gas passage 54 to the outside, the fuel cell can always be operated in a stable state according to the load fluctuation.

In the processing in S30 and S70 to S110 described above, at least one of the load request, anode exhaust gas flow rate, and fuel gas flow rate conditions in S30 matches the set lower limit value and the set lower limit flow rate, respectively. As long as the state is maintained, the CPU 9 of the control device 90
1 is repeated each time a load request signal is received.

Here, in the fuel cell device 10, of the data stored in the storage device 95, the flow control valve F
As described above, the proportional constants of RV1 to FRV4 are determined as load constants for the fuel cell FC, that is, proportional constants proportional to the amount of methanol according to the load request, and are further determined so as to satisfy the following conditions. ing.
That is, in the fuel cell device 10, the flow control valve FR
The proportionality constants of V1 to FRV4 are determined based on the temperature of the fluid in the evaporator 16, the temperature of the fluid in the reformer 17, and the temperature of the fluid in the selective oxidizer 18 during operation. The partial pressure of CO in the fuel gas flowing out of the fuel cell FC is controlled within an allowable range that does not become a catalyst poison of the anode A, and the partial pressure of water vapor is reduced to the polymer electrolyte membrane E of the fuel cell FC.
M is determined to be a value suitable for humidification.

Thus, even if a drain is generated in each fuel gas passage 54 of the anode A due to a decrease in the load demand on the fuel cell FC during the operation of the fuel cell device 10, the drain is quickly discharged. Each fuel gas passage 54
The fuel cell FC can always be operated in a stable state in accordance with the load fluctuation.

Although the preferred embodiment of the present invention has been described in detail, the fuel cell device and the method of operating the fuel cell device of the present invention are not limited to the above embodiment.

For example, the fuel cell device 1 of the above embodiment
The operation method of determining the supply of the anode exhaust gas to the anode A based on all the detected values of the load request value, the flow rate of the anode exhaust gas, and the flow rate of the fuel gas has been described with respect to the operation method of 0. The operation method of the fuel cell device is not limited to the above embodiment. For example,
The supply of the anode exhaust gas to the anode A may be determined based only on the detected value of the load request value, and the supply of the anode exhaust gas to the anode A is determined based on the detected value of the load request value and the flow rate of the anode exhaust gas. May be.

Further, as in the fuel cell device 10A shown in FIG. 7, an exhaust gas supply line L near the inlet of the circulation blower B2 is provided.
A demister D2 for removing water in the anode exhaust gas
May be provided. Thereby, the moisture in the anode exhaust gas supplied to the anode A can be sufficiently reduced, and the generation of drain in each fuel gas passage 54 of the anode A can be effectively suppressed.

Further, the fuel cell device 10 of the above embodiment
, A fuel cell FC having a plurality of stack structures
Has been described with respect to the configuration in which the anode reaction gas is supplied in parallel. However, the fuel cell device of the present invention is not limited to this.
0A, a fuel cell F having a plurality of stack structures
A configuration may be provided in which the anode reaction gas is supplied in series for C. In this case, it is preferable to provide a demister D1 for removing moisture in the fuel gas (anode exhaust gas) discharged from the fuel cell FC located on the upstream side on the fuel gas line L3 between the plurality of fuel cells FC. .
As a result, the generation of drain in the gas flow path of the anode of the fuel cell FC located on the downstream side can be effectively suppressed.

Further, in the fuel cell device of the present invention, the shape of the gas flow path formed in the separator of the fuel cell is not particularly limited. For example, as shown in FIG. May be.

[0121]

EXAMPLES Hereinafter, the contents of the fuel cell device of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Embodiment 1) The fuel cell device 10 shown in FIG.
A fuel cell device having the same configuration as that of A was manufactured. Two fuel cell stacks are mounted, and the maximum output is 31
kW. The total sum of the cross-sectional areas of the fuel gas passages of the anodes in all the single cells arranged in the two fuel cell stacks was 0.00554 m ² .

The operating conditions of this fuel cell device were as follows: operating temperature of the fuel cell: 80 ° C., hydrogen pressure supplied to the fuel cell; 76,000 Pa, air pressure supplied to the fuel cell;
When 182385 Pa (oxygen pressure; 38300 Pa), the hydrogen utilization rate at the anode; 80%, the S / C ratio of water and methanol supplied to the reformer; 1.8, the maximum value of the load requirement for the fuel cell is 114 A Becomes This value is 23.4 m ³ (Normal) / h in terms of the amount of hydrogen produced in the fuel gas at the outlet of the reformer.

When the fuel cell device is operated in accordance with load fluctuations under the above operating conditions, the set lower limit of the required load value, the set lower limit flow of the anode exhaust gas, and the set lower limit flow of the fuel gas are as follows. Was determined as described above. For convenience of description, the maximum value of the load request for the fuel cell is set to 100%, and the load request for the fuel cell is expressed as a percentage.

That is, this fuel cell device is shown in FIG.
When the load demand reaches 32% when the load demand is gradually reduced from 100% without operating the anode exhaust gas to the anode without operating the flow regulating valve FRV4 and the circulation blower B2 shown in FIG. In addition, it was found from theoretical calculations and experimental data that the flow rate of the anode exhaust gas at the outlet of the gas flow path formed in the separator on the anode side of the single cell was 0.45 m / s. Therefore, the set lower limit of the required load value is set to 32%. Further, when the flow rate of the anode exhaust gas becomes 0.45 m / s (when the load request becomes 32%), the flow rates of all the anode exhaust gas discharged from the fuel cell stack are obtained from theoretical calculation and experimental data,
Set the lower limit flow rate of the anode exhaust gas to 149.8 L / min.
And Further, the fuel gas flowing out of the reformer when the load demand becomes 32% was obtained from theoretical calculation and experimental data, and the set lower limit flow rate of the fuel gas was set to 249.6 L / min.

Then, based on the set lower limit of the required load value, the set lower limit flow rate of the anode exhaust gas, and the set lower limit flow rate of the fuel gas, the flow control valve FRV4 and the circulation blower B2 are set.
The controller was set to operate. The flow rate of the anode exhaust gas at each outlet of each gas flow path formed in the separator on the anode side of the single cell when the load requirement is 32% or less is always a sufficiently large value of 0.45 m / s or more. 0.85 m / s (“predetermined value of 0.45 m / s or more”).

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the exhaust gas supply line L7, the circulation blower B2, the flow rate regulating valve FRV4, the flow rate detector S1, and the flow rate detector S2 shown in FIG. 1 were not mounted. Thus, a fuel cell device was configured.

[Operation test at the time of load change] An operation test was performed for the fuel cell devices of Example 1 and Comparative Example 1 when the load requirement for the fuel cell was changed, and the gas formed on the anode-side separator was changed. The presence or absence of blockage due to drainage in the flow path was examined. The driving test
First, the fuel cell device is operated for about 5 hours under an operating condition in which the load request value for the fuel cell is 100%, and then the load request value for the fuel cell is sequentially changed to 60% and 30%. It was operated for about 10 hours under operating conditions. Table 1 shows the test results of the fuel cell devices of Example 1 and Comparative Example 1.

[Table 1]

As is evident from the results shown in Table 1, under the above-mentioned practical operating conditions, the fuel cell device of the present invention according to the first embodiment shows that the load required value for the fuel cell is equal to the set load required value. When the flow rate fluctuates to 30%, which is lower than the lower limit of 32%, the flow regulating valve FRV4 and the circulation blower B2 operate to prevent the gas flow path formed in the anode-side separator from being blocked by the drain. Long time (about 10h
It was confirmed that the operation was stable over the above.

[0130]

As described above, the fuel cell device according to the present invention has one end connected to the exhaust gas line for discharging the exhaust gas discharged from the anode to the outside, and the other end connected to the gas connecting the reformer and the anode. An exhaust gas supply line connected to the line, an exhaust gas supply means provided on the exhaust gas supply line, for supplying a part of exhaust gas discharged from the anode to the anode, and an anode and Control means for controlling the exhaust gas supply means so that the flow rate of the exhaust gas at the outlet of the gas flow path formed by the separator has a predetermined value of 0.45 m / s or more. In the method of operating the fuel cell device according to the present invention, a part of the exhaust gas discharged from the anode is taken out based on a load request for the fuel cell and supplied to the anode together with the anode reaction gas flowing out of the reformer, The flow rate of the exhaust gas supplied to the anode is adjusted so that the flow rate of the exhaust gas at the outlet of the gas flow path formed by the separator and the separator has a predetermined value of 0.45 m / s or more.
As a result, it is possible to sufficiently prevent the gas flow path on the anode side of the operating fuel cell from being blocked by the drain.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a preferred embodiment of a fuel cell device according to the present invention.

FIG. 2 is a perspective view showing a fuel cell provided in the fuel cell device of FIG.

FIG. 3 is a sectional view showing a single cell and a separator provided in the fuel cell of FIG. 2;

4 (a) is a plan view of the separator shown in FIG. 3 as viewed from the anode side, and FIG. 4 (b) is a plan view of the separator shown in FIG. 3 as viewed from the cathode side.

FIG. 5 is a control block diagram of the fuel cell device shown in FIG.

6 is a flowchart illustrating a control procedure of the fuel cell device shown in FIG.

FIG. 7 is a system diagram showing another embodiment of the fuel cell device according to the present invention.

FIG. 8 is a plan view showing another embodiment of the separator shown in FIG.

[Explanation of symbols]

3 ... Load 10, 10A, ... Fuel cell device, 12 ... Fuel supply unit, 14 ... Water supply unit, 15 ... Reformer, 16 ... Evaporation unit, 17 ... Reformation unit, 18 ... Selective oxidation unit, 21 ... Sealing material, 35: cooler, 40: stack, 41a: anode current collector, 41b: cathode current collector, 42: insulating plate, 43
... Stack fastening plates, 44a, 44b ... Flanges, 45 ...
Membrane plate, 47a: fuel gas inlet, 47b: air inlet, 48
a: Anode exhaust gas outlet, 48b: Cathode exhaust gas outlet, 49a: Cooling medium inlet, 49b: Cooling medium outlet, 5
0: cooling system, 50a, 50b, 51a, 51b, 5
6, 57 ... opening, 52, 53 ... groove, 54 ... fuel gas flow path, 55 ... air flow path, R ... radiator, 90 ... control device, A ... anode, B1 ... blower, B2 ... circulation blower,
C: cathode, EM: electrolyte membrane, FC: fuel cell, FR
V1, FRV2, FRV3, FRV4 ... Flow regulating valve, L
1: fuel gas supply line, L2: air supply line, L3
... Anode exhaust gas line, L4 ... Cathode exhaust gas line, L7 ... Anode exhaust gas supply line, Pc ... Pump
S: hydrogen concentration sensor, SP: separator, UC: single cell.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiji Fujikawa 4-6-22 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima F-term in Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. 5H026 AA06 BB00 CC03 HH00 HH03 5H027 AA06 BA01 BA19 KK21 KK26 KK52 MM08 MM12

Claims (8)

[Claims] 1. A fuel cell comprising a plurality of unit cells each having a polymer electrolyte and a separator disposed between an anode and a cathode, and a fuel cell in which a plurality of separators are stacked, and an anode reaction gas generated by a reformer is supplied to the anode. And a cathode reaction gas supply means for supplying a cathode reaction gas to the cathode to generate power by an electrochemical reaction. One end of the fuel cell device is connected to an exhaust gas line for discharging exhaust gas discharged from the anode to the outside. An exhaust gas supply line having the other end connected to a gas line connecting the reformer and the anode; and an exhaust gas supply line provided on the exhaust gas supply line, wherein a part of exhaust gas discharged from the anode is supplied to the anode. Exhaust gas supply means for supplying, based on a load request for the fuel cell, the anode and the separator A fuel cell device comprising: a control unit that controls the exhaust gas supply unit such that the flow rate of the exhaust gas at the outlet of the formed gas flow channel has a predetermined value of 0.45 m / s or more. 2. A circulation system in which the exhaust gas supply means sucks a part of the exhaust gas discharged from the anode into the exhaust gas supply line and discharges the exhaust gas toward a gas line connecting the reformer and the anode. The fuel cell device according to claim 1, further comprising: a blower; and a flow rate adjusting unit configured to adjust a flow rate of the exhaust gas discharged from the circulation blower. 3. The fuel cell further comprises: a first flow rate detecting means provided on the exhaust gas line near an exhaust gas outlet of the anode, for detecting a flow rate of the exhaust gas. 3. The fuel cell device according to claim 1, wherein the exhaust gas supply unit is further controlled based on a value detected by the first flow rate detection unit. 4. The fuel cell further comprises a second flow rate detecting means for detecting a flow rate of the anode reactant gas flowing out of the reformer, wherein the control means determines a load request for the fuel cell and the first flow rate detecting means. 4. The fuel cell device according to claim 3, further comprising controlling the exhaust gas supply unit based on a detection value and a detection value of the second flow rate detection unit. 5. 5. The apparatus according to claim 1, further comprising a droplet removing unit provided on the exhaust gas supply line near an inlet of the exhaust gas supply unit and configured to remove droplets contained in the exhaust gas. The fuel cell device according to any one of claims 1 to 4. 6. A fuel cell comprising a plurality of unit cells each having a polymer electrolyte and a separator disposed between an anode and a cathode, and supplying an anode reaction gas generated by a reformer to the anode. And a cathode reactant gas supply means for supplying a cathode reactant gas to the cathode from the cathode reactant gas supply means to generate electric power by an electrochemical reaction, wherein the fuel is discharged from the anode based on a load request for the fuel cell. Part of the exhaust gas is taken out and supplied to the anode together with the anode reaction gas flowing out of the reformer, and the flow rate of the exhaust gas at the outlet of a gas flow path formed by the anode and the separator is set to 0.
A method of operating a fuel cell device, comprising: adjusting a flow rate of the exhaust gas supplied to the anode so as to have a predetermined value of 45 m / s or more. 7. The method according to claim 6, wherein a flow rate of the exhaust gas discharged from the anode is detected, and a flow rate of the exhaust gas supplied to the anode is adjusted based on the detected value. An operation method of the fuel cell device. 8. The method according to claim 6, wherein a flow rate of the anode reaction gas flowing out of the reformer is detected, and a flow rate of the exhaust gas supplied to the anode is adjusted based on the detected value. Or the operation method of the fuel cell device according to 7.