JP2001283881A - Fuel cell device and operating method of fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to supply fuel and the like in high precision to a reformer of a fuel cell device and also to aim cost reduction and compactness of the fuel cell device. SOLUTION: A fuel cell device is equipped with a reformer 30 for generating fuel gas to be supplied to each anode A of the fuel cell FC. To the reformer 30, methanol, reforming water and reforming air are supplied at a constant pressure respectively from a fuel supply portion 1, a water supply portion 20 and a blower B. And the liquid pressure inside the reformer 30 is kept constant by a pressure control valve PRV 3 and electromagnetic valves SV1, SV2, SV3, SV4 are provided in the liquid lines L1, L2, L3, L4 connecting the reformer 30 with the water supply portion 20 and the blower B, which open and shut intermittently each line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell device and a method of operating the fuel cell device, and more particularly, to a fuel cell device which generates electric power by a fuel cell having a polymer electrolyte sandwiched between an anode and a cathode, and It relates to the driving method.

[0002]

2. Description of the Related Art Fuel cells having an electrolyte sandwiched between an anode and a cathode have been known.
This type of fuel cell directly extracts electric energy generated by an electrochemical reaction using a fuel gas (anode reaction gas) and an oxidizing gas (cathode reaction gas) as an electrode active material. It has high power generation efficiency in the 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 a 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.

As an electrode active material and an electrolyte of a fuel cell, hydrogen, oxygen, and a proton conductive electrolyte are generally used. In this case, the following formula (1) is used for the anode and 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 ⁻ (2) H ₂ + (1/2) O ₂ → H ₂ O (3)

[0004] Fuel cells that generate electric power by such an electrochemical reaction are classified according to an electrode active material, an electrolyte, an operating temperature, and the like. Among them, a so-called polymer electrolyte using a polymer electrolyte as an electrolyte is particularly preferred. Type fuel cells (PEMC) etc. are easy to reduce in size and weight.
Practical application as a power source for mobile vehicles such as electric vehicles and small cogeneration systems is expected. In a polymer electrolyte fuel cell, a cation exchange membrane (solid polymer electrolyte membrane) having proton conductivity is used as an electrolyte. As a fuel gas, a hydrogen-containing gas generated by steam reforming a hydrocarbon raw fuel such as methanol or natural gas is used, and air is used as an oxidizing gas.

[0005] A reformer for producing a fuel gas to be supplied to the anode of such a polymer electrolyte fuel cell will be described.
In the reformer, first, the reaction shown in the following equation (4) proceeds, and a reformed gas containing hydrogen and carbon monoxide is generated from methanol and water. Then, unreacted carbon monoxide contained in the reformed gas generated by the reaction of the formula (4) reacts with water to form carbon dioxide as shown in the formula (5). As a result, the reformer generates fuel gas having an extremely low carbon monoxide concentration as compared with the hydrogen concentration.
That is, the reaction represented by the following equation (6) proceeds in the entire reforming apparatus. Further, if necessary, air or pure oxygen may be mixed into the fuel gas to advance the partial oxidation reaction of methanol represented by the following equation (7). CH ₃ OH → CO + 2H ₂ −21.7 kcal / mol (4) CO + H ₂ O → CO ₂ + H ₂ +9.8 kcal / mol (5) CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ −11.9 Kcal / Mol (6) CH ₃ OH + ＯO ₂ → CO + H ₂ O + H ₂ +36.2 kcal / mol (7)

[0006] As shown in the above formulas (6) and (7), when reforming methanol, carbon monoxide is generated to some extent, and the fuel gas supplied from the reformer to the anode of the fuel cell is also generated. Will be included. The carbon monoxide is generated even when a hydrocarbon other than methanol is used as a fuel of the anode reaction gas,
It acts as a catalyst poison on the anode electrode catalyst. Therefore,
In a polymer electrolyte fuel cell, it is necessary to reduce the concentration of carbon monoxide in the fuel gas as much as possible from the viewpoint of extending the life of the anode. In order to reduce the concentration of carbon monoxide in the fuel gas, it is important to always optimally control the supply amounts of the fuel (eg, methanol) and the reforming fluid (eg, water, air) to the reformer.

For this reason, in a conventional fuel cell device, a fuel line connecting a fuel tank and a reformer or a reforming fluid line connecting a water tank or the like and a reformer is provided with a high-performance device such as a thermal mass flow controller. An accurate flow rate adjusting means was provided. The flow rate adjusting means is accurately controlled so as to respond to a load demand for the fuel cell, and adjusts the fuel supply amount and the reforming fluid supply amount to the reforming device by changing the opening of the fuel line and the reforming fluid line. I do.

[0008]

However, the conventional fuel cell device constructed as described above has the following problems. That is, the flow rate adjusting means such as the thermal flow meter provided in the conventional fuel cell device changes the degree of opening of the fuel line and the reforming fluid line, and can be said to be excellent in terms of accuracy. It was extremely expensive and had a large size and weight. Moreover, the cost and size of these flow rate adjusting means increase as the opening degree adjusting ability is improved. Therefore, if a large number of such flow rate adjusting means are applied to a fuel cell device, the cost and size of the entire device will inevitably increase. On the other hand, a fuel cell device mainly intended to be mounted on a vehicle or applied to a small cogeneration system is required to be low-cost and compact. For this reason, the appearance of a low-cost and compact configuration that can supply fuel and the like to the reformer with high accuracy has been desired.

Accordingly, the present invention provides a fuel cell device capable of accurately supplying fuel and the like to a reforming device, easily reducing costs and downsizing, and a method of operating the fuel cell device. For the purpose of providing.

[0010]

According to a first aspect of the present invention, there is provided a fuel cell device comprising a fuel cell having a polymer electrolyte sandwiched between an anode and a cathode, wherein an anode reaction generated in a reformer is provided. In a fuel cell device that supplies gas to the anode and supplies cathode reaction gas to the cathode from the cathode reaction gas supply means and generates electric power by an electrochemical reaction, a fluid can be supplied to the reformer at a substantially constant pressure. Fluid supply means, pressure adjusting means for keeping the fluid pressure inside the reformer substantially constant, and a fluid line connecting the reformer and the fluid supply means,
And a flow path opening / closing means capable of opening and closing the fluid line intermittently.

The fuel cell device is suitable for use as a power source for a mobile vehicle or a small cogeneration system, and includes a fuel cell containing an electrolyte such as a solid polymer electrolyte membrane sandwiched between an anode and a cathode. . An anode reaction gas (fuel gas) such as a hydrogen-containing gas generated by the reformer is supplied to the cathode of the fuel cell. A cathode reaction gas (oxidizing gas) such as air is supplied to the cathode of the fuel cell by a cathode reaction gas supply device including a blower or the like. Thereby, 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 entire fuel cell to obtain an electromotive force.

In the fuel cell device configured as described above,
In order to reduce the concentration of carbon monoxide contained in the anode reaction gas as much as possible, it is necessary to always optimally control the supply amounts of the fuel (methanol, etc.) and the reforming fluid (water, air, etc.) to the reformer. is there. For this purpose, in this fuel cell device, a flow passage opening / closing means is provided in a fluid line connecting a fluid supply means serving as a supply source of a predetermined fluid such as a fuel or a reforming fluid to the reforming apparatus. The flow path opening / closing means can open / close the fluid line intermittently. Also,
The fluid supply means includes a pump, a compressor, or the like, and can supply a predetermined fluid such as a fuel or a reforming fluid to the flow path opening / closing means at a substantially constant pressure. The fluid pressure inside the reformer is always kept substantially constant by the pressure adjusting means.

In the fuel cell device configured as described above,
Since a predetermined fluid such as a fuel or a reforming fluid is supplied from the fluid supply means to the flow path opening / closing means at a substantially constant pressure, the fluid pressure at the inlet of the flow path opening / closing means is always substantially constant. Further, since the fluid pressure inside the reformer is always kept substantially constant by the pressure adjusting means, the fluid pressure at the outlet of the flow path opening / closing means also becomes almost always constant. That is, under such a configuration, the differential pressure between the inlet and the outlet of the flow path opening / closing means is always kept substantially constant.

As described above, by maintaining the pressure difference between the inlet and the outlet of the flow path opening / closing means substantially constant, the flow rate characteristics are extremely simplified, and the flow rate characteristics are greatly reduced. The supply amount of the fluid to the reformer can be determined very easily. Therefore, in this fuel cell device, the supply amount of the fluid to the reformer, that is, the supply amount of the fuel (methanol or the like) and the supply amount of the reforming fluid (water or air or the like) to the reformer is controlled only by controlling the opening and closing of the flow path opening and closing means. Adjustment can always be performed optimally and accurately. In addition, it is not necessary to use a large and expensive thermal mass flow controller or the like as the flow path opening / closing means, so that a small and inexpensive solenoid valve or the like can be adopted. Therefore, the entire fuel cell device can be significantly reduced in cost and size.

The pressure adjusting means is provided in a gas line for supplying the anode reaction gas from the reformer to the anode, and keeps the pressure of the anode reaction gas at the outlet of the reformer substantially constant. It is preferred that there is.

By adopting such a configuration, the fluid pressure inside the reformer can be very easily maintained substantially constant. Also. As such a pressure adjusting means, a general pressure adjusting valve (opening adjusting valve) can be adopted, so that an increase in cost of the fuel cell device can be suppressed.

Further, it is preferable to further comprise a control means for setting a ratio between an opening time and a closing time of the flow path opening / closing means based on a load request for the fuel cell.

By adopting such a configuration, even if the load demand on the fuel cell changes and the amount of the anode reactant gas to be supplied to the fuel cell changes, the anode reactant gas having an extremely low carbon monoxide concentration is always maintained. Can be generated by the reformer. Therefore, the fuel cell can be operated stably, and the life of the anode can be prolonged.

The flow path opening / closing means is an electromagnetic valve including a movable iron core attached to a valve body that opens and closes a flow path formed in the valve body, and an electromagnetic coil arranged to cover the movable iron core. Is preferred.

Such an electromagnetic valve can be manufactured at a very low cost and in a compact manner, and can be reliably operated. Therefore, by adopting such a configuration, it is possible to greatly reduce the cost and size of the entire fuel cell device. In this case, if the movable iron core is arranged in a flow path formed in the valve body, further downsizing can be achieved.

Further, there is further provided a pulse generating means for generating a pulse signal for intermittently applying a drive voltage to the flow passage opening / closing means, wherein the control means opens the flow passage opening / closing means in response to a load request for the fuel cell. It is preferable that a time and a closing time are determined, and a pulse signal corresponding to the opening time and the closing time is generated by the pulse generating means.

By adopting such a configuration, it is possible to control the opening and closing of the solenoid valve as the passage opening and closing means very reliably and accurately. As a result, it is possible to adjust the supply amount of the fluid to the reformer very accurately.

According to a sixth aspect of the present invention, there is provided a method for operating a fuel cell device according to the present invention, wherein a fuel cell having a polymer electrolyte sandwiched between an anode and a cathode is used, and an anode reaction gas generated by a reformer is supplied to the anode. In the method of operating a fuel cell device, which supplies a cathode reactant gas to a cathode from a cathode reactant gas supply means and supplies an anode reactant gas and a cathode reactant gas by electrochemical reaction, a predetermined amount is supplied to a reformer. A flow path opening / closing means is provided in a fluid line for supplying a fluid, and the flow path opening / closing means is intermittently connected while maintaining a substantially constant difference between a fluid pressure at an inlet of the flow path opening / closing means and a fluid pressure inside the reformer. And a predetermined fluid is supplied to the reformer.

In this case, it is preferable that the pressure of the anode reaction gas at the outlet of the reformer is kept substantially constant, so that the fluid pressure inside the reformer is kept substantially constant.

It is preferable that the supply time of the fluid to the reformer and the supply stop time are determined in accordance with the load demand on the fuel cell.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a fuel cell device and a method of operating a 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 FIG. 1 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) containing hydrogen and air (cathode reaction gas) as an oxidizing gas. The electric energy generated by the fuel cell FC is used as a driving 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, a fuel cell device 1 includes a fuel supply unit 10 for generating fuel gas, a water supply unit 2
0 and a reformer 30. Fuel supply unit 10
Has a fuel tank 11 for storing methanol for generating fuel gas. A fuel pump P1 is disposed in the fuel tank 11, and one end of a pressure adjustment line LP1 is connected to a discharge port of the fuel pump P1. The pressure adjustment line LP1 has a pressure adjustment valve PRV1 halfway, and the other end is guided into the fuel tank 11. The pressure regulating valve PRV1 keeps a fluid pressure discharged from the fuel pump P1 and flowing through the pressure regulating line LP1 at a predetermined value. In addition, excess methanol due to pressure adjustment by the pressure adjustment valve PRV1 is returned to the fuel tank 11 via the pressure adjustment line LP1.

A fuel line L1 branches from the pressure adjustment line LP1 between the fuel pump P1 and the pressure adjustment valve PRV1. The fuel line L1 has an electromagnetic valve SV1 functioning as a flow path opening / closing means on the way, and is connected to the fuel supply line LS. Here, as described above, the fluid pressure in the pressure adjustment line LP1 between the fuel pump P1 and the pressure adjustment valve PRV1 is kept constant by the pressure adjustment valve PRV1 of the fuel supply unit 10. Therefore, the fluid pressure in the fuel line L1 on the upstream side of the solenoid valve SV1 is always constant.

Similarly, the water supply section 20 has a water tank 21 for storing water used as a reforming fluid when reforming fuel (methanol). A water pump P2 is disposed in the water tank 21, and one end of a pressure adjustment line LP2 is connected to a discharge port of the water pump P2. This pressure adjustment line LP2 also has a pressure adjustment valve PRV2
And the other end is guided into the water tank 21.
The pressure regulating valve PRV2 keeps the fluid pressure discharged from the water pump P2 and flowing through the pressure regulating line LP2 at a predetermined value. The surplus water due to the pressure adjustment by the pressure adjustment valve PRV2 is returned to the water tank 21 via the pressure adjustment line LP2.

The reforming water line L2 branches off from the pressure adjusting line LP2 between the water pump P2 and the pressure adjusting valve PRV2. Reforming water line L2
Has an electromagnetic valve SV2 functioning as a flow path opening / closing means on the way, and joins a connection portion between the fuel line L1 and the fuel supply line LS. Here, as described above, the water pump P
The fluid pressure in the pressure adjustment line LP2 between the pressure adjustment valve PRV2 and the pressure adjustment valve PRV2 of the water supply unit 20
It is kept constant by V2. Therefore, the solenoid valve SV
The fluid pressure in the reforming water line L2 on the upstream side of 2 is always constant.

The methanol supplied from the fuel supply unit 10 and the reforming water supplied from the water supply unit 20 are mixed at the junction of the fuel line L1, the reforming water line L2, and the fuel supply line LS, The fuel is supplied to the reformer 30 via the fuel supply line LS. The reformer 30 generates a fuel gas containing hydrogen by steam reforming of methanol supplied from the fuel supply unit 10 using reforming water supplied from the water supply unit 20. For this reason, the reformer 30 includes the evaporator 31, the reformer 32, and the selective oxidizer 3
3 inclusive.

The fuel gas generation process in the reformer 30 will be described. The fuel supply unit 10 and the water supply unit 20
Is first supplied to the evaporator 31 via the fuel supply line LS. The evaporating section 31 includes a burner (not shown), and the heat generated by the burner vaporizes and raises the temperature of the water-methanol mixture to form a water-methanol mixture. Then, the water-methanol mixed gas vaporized and heated in the evaporator 31 flows into the reformer 32.

Inside the reforming section 32, 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 32 passes through the surface of the reforming catalyst, the reactions shown in the above equations (4), (5), and (6) progress, and as a result, The resulting reformed gas is generated.

Since the steam reforming reaction shown in the above formulas (4) to (6) is an endothermic reaction, it is necessary to supply heat into the reforming section 32 to advance the reaction. To this end, it is preferable that the water / methanol mixed gas be flowed from the evaporator 31 into the reformer 32 while entraining heat. Further, a predetermined heating device is provided in the reforming section 32, and heat for promoting the reaction is supplied from the heating apparatus to the reforming section 32.
You may comprise so that it may give inside. When the steam reforming reaction is advanced by the Cu—Zn catalyst, the reforming unit 3
It is preferable that the internal temperature of No. 2 be in a temperature range of 250 to 300 ° C.

Further, an air line L3 having a solenoid valve SV3 functioning as a passage opening / closing means is connected to the reforming section 32, and the reforming section 32 is connected to the reforming section 32 via the air line L3. Reforming air is supplied as needed.
When the reforming air is supplied into the reforming section 32, the reforming section 3
In 2, the reaction represented by the above formula (7) proceeds between methanol in the water-methanol mixed gas flowing from the evaporator 31 and oxygen contained in the reforming air. As a result, the heat required to advance the endothermic reaction can be further supplemented.

Next, the reformed gas generated in the reforming section 32 flows into the selective oxidizing section 33. In the selective oxidation section 33, a porous body (not shown) supporting a CO selective oxidation catalyst such as a metallosilicate catalyst is arranged. In addition, the selective oxidizing unit 33 includes a solenoid valve SV4
An air line L4 having (flow path opening / closing means) is connected, and air for CO oxidation is supplied into the selective oxidizing unit 33 via the air line L4. And the selective oxidation unit 3
When the reformed gas that has flowed into 3 passes through the surface of the CO selective oxidation catalyst, the CO oxidation air supplied from the air line L4 is used, and the selective oxidation reaction represented by the following equation (8) proceeds. . CO + 1 / 2O ₂ → CO ₂ (8)

As a result, only the carbon monoxide in the reformed gas generated in the reforming section 32 is selectively oxidized, and in the selective oxidizing section 33, the fuel gas having a sufficiently reduced carbon monoxide concentration is generated. Will be done. Then, the fuel gas generated in the selective oxidizing unit 33 of the reformer 30 is supplied to the fuel cell FC via the fuel gas supply line L5. A pressure regulating valve PRV3 is disposed in the fuel gas supply line L5 so as to be located near the reformer 30. The pressure regulating valve PRV3 always maintains the pressure of the fuel gas in the fuel gas supply line L5 at the reformer outlet at a predetermined value. Thereby, the reformer 30 (evaporator 3
1, the pressure of the fluid such as the mixed gas of water / methanol and the reformed gas inside the reforming section 32 and the selective oxidizing section 33) can be always kept constant while suppressing an increase in the cost of the fuel cell device 1.

On the downstream side of the pressure regulating valve PRV3,
A condenser 35 is arranged. The fuel gas flowing out of the reformer 30 and flowing through the fuel gas supply line L5 is heated in accordance with the reaction temperature of the steam reforming reaction that proceeds in the reformer 30. The battery is cooled to near the operating temperature of the battery FC. Along with this, the water vapor contained in the fuel gas is also cooled and condensed, and the partial pressure of the water vapor in the fuel gas also decreases to the saturated water vapor pressure at the operating temperature of the fuel cell. As a result, it is possible to prevent the water vapor in the fuel gas from being condensed in the fuel cell FC, and to prevent a situation in which the condensed water hinders the flow of the fuel gas. The water collected by the condenser 35 is returned to the water tank 21 of the water supply unit 20 and reused for various uses.

On the other hand, the fuel cell device 1 includes a blower B as a cathode reaction gas supply means for supplying air as a cathode reaction gas to the fuel cell FC. This blower B
Is connected to the fuel cell FC via an air supply line L6 having an air flow regulating valve FRV halfway, and sucks air in the atmosphere to increase the pressure to a predetermined pressure.
Pressure feed. As a result, the compressed air heated to a predetermined temperature (for example, about 120 ° C.) is supplied to the fuel cell FC.

Further, the above-described reforming air is supplied to the selective oxidation section 3.
3 is branched from an air supply line L6 connected to the blower B, and an air line L3 for supplying reforming air to the reforming section 32 is
It is branched from this air line L4. That is, the blower B includes the reformer 32 and the selective oxidizer 3 of the reformer 30.
3 also functions as a fluid supply means for supplying reforming air. This eliminates the need to separately provide a supply source for supplying the reforming air, so that the entire fuel cell device 1 can be made compact.

As described above, the fuel cell FC receives the supply of the fuel gas from the reformer 30 and the supply of the air from the blower B. The fuel cell FC will be described in detail. As shown in FIG.
Single cell UC (see FIG. 3) and separator SP (see FIG. 4)
And a stack 40 in which a large number are alternately stacked via a sealing material (not shown). The stack 40 includes an anode current collector 41a connected to the anode A of each single cell UC.
And a cathode current collector 41b connected to the cathode C of each unit cell UC, and an insulating plate 4 is provided outside the anode current collector 41a and the cathode current collector 41b.
2 are arranged.

Outside the insulating plates 42, flanges 44a, 44b are arranged via a stack tightening plate 43. The flanges 44a and 44b are connected by a membrane plate 45 and firmly fastened. As a result, 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, thereby absorbing expansion and contraction of the stack 40 due to temperature rise and temperature drop of the fuel cell FC. it can.

Further, the fuel cell FC includes a cathode current collector 4
The fuel gas inlet 47a (anode reaction gas inlet) penetrates the upper left corner of the insulating plate 42 located on the 1b side, and a fuel gas supply line L5 connected to the reformer 30 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 through the upper right corner, and an air supply line L6 connected to the blower B is connected to the air inlet 47b. As a result, 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.

As shown in FIG. 3, each single cell UC includes an electrolyte membrane EM having an anode A and a cathode C which are gas diffusion electrodes.
It is made to be pinched by. The electrolyte membrane EM is an ion exchange membrane formed of, for example, a solid polymer material such as a fluorine-based resin and showing good ion conductivity in a wet state. Examples of the solid polymer material constituting the electrolyte membrane include a Nafion membrane (manufactured by DuPont), a perfluorocarbon sulfonic acid resin, a polysulfone resin, a perfluorocarboxylic acid resin, a polystyrene-based cation exchange resin having a sulfonic acid group, and a fluorocarbon. A graft copolymer resin of a matrix and trifluoroethylene,
A polyethylene sulfonic acid resin, a polyvinyl sulfonic acid resin, or the like can be used.

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 for 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 the gas diffusion layer, for example, a water-repellent material is used by using a fluorocarbon resin (for example, PTFE [polytetrafluoroethylene]) on a porous body having electrical conductivity (in this embodiment, carbon paper made of carbon fiber). The treated one is used.

The reaction layer plays the role of promoting the electrode reactions represented by the above formula (1) at the anode and the above formula (2) at the cathode. This reaction layer is a three-dimensional reaction site, that is, a three-phase interface area between a region formed 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, a basic skeleton is formed from catalyst-supporting carbon black fine particles having a large catalyst surface area, and P
A hydrophobic gas diffusion network is constructed by dispersing a water repellent such as TFE and performing a water repellent treatment. Then, a solution obtained by dissolving a polymer electrolyte in an organic solvent is applied to the other portion of the skeleton by, for example, permeation coating, so that 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 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-like 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 or the like, thereby sintering the PTFE in the slurry and removing 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. Thereby, 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 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, to reduce the amount of supported catalyst or to construct a gas diffusion network having better hydrophobicity, unsupported carbon black fine particles previously coated with a fluororesin may be used as catalyst-supporting carbon black particles. It may be dispersed in black fine particles.

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 a 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 a cathode, an electrolyte membrane EM made of a solid polymer material
To form a single cell UC. 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 then 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 film 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 into 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 anode A side and the cathode C side correspond to one single cell UC. Is attached to each one. The separator SP is formed of, for example, a gas-impermeable conductive member such as dense carbon which is made by compressing carbon to be gas-impermeable, 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. Are formed. Further, the cathode contact surface of the separator SP has one end communicating with the upper right opening 50b in the figure and the other end communicating with the lower left opening 51b in the figure.
A plurality of grooves 53 that are bent in an S-shape are formed so as to communicate with the grooves.

When the stack 40 is formed by stacking a large number of the separators SP and the single cells UC thus configured, each of the openings 50a, 50b, 51a, 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 by 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 30 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 the surface of the anode A flows into the fuel gas flow path 54 defined by the fuel gas flow path 54. 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 as the oxidizing gas supplied from the blower B is supplied to the air inlet 47b and each of the separators SP.
Flows into the air flow path 55 defined by the grooves 53 of each separator 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.

Further, the separator SP of this 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 travels regularly 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, and the heat of reaction 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 that has reacted at the anode A while flowing through the fuel gas passage 54 becomes anode exhaust gas and flows into the passage 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 flow path 55 is:
It becomes 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.

The anode exhaust gas outlet 48a of the fuel cell FC
As shown in FIG. 1, the reformer 30 is connected via an anode exhaust gas line L7 having a pressure regulating valve PRV4 in the middle.
Is connected to the evaporating section 31 of the first section. Similarly, the fuel cell FC
Of the cathode exhaust gas outlet 48b of the pressure regulator PR
It is connected to the evaporator 31 (burner) of the reformer 30 via a cathode exhaust gas line L8 having V5. The anode exhaust gas generated at each anode A of the fuel cell FC is used as fuel by a burner provided in the evaporator 31 of the reformer 30, and the cathode exhaust gas generated at each cathode C is reused as an oxidant. Used.

The pressure regulating valve PRV4 keeps the pressure of the anode exhaust gas flowing through the anode exhaust gas line L7 at a predetermined value at the outlet of the fuel cell FC, and the pressure regulating valve PRV5 flows through the cathode exhaust gas line L8. The pressure of the cathode exhaust gas is maintained at a predetermined value at the outlet of the fuel cell FC. Thereby, the fluid pressure inside the fuel cell FC, that is, the opening 50 of each separator SP
a, 50b, 51a, and 51b, and the pressure of the fuel gas and air in each fuel gas flow path 54 and each air flow path 55 can be kept constant.
The fuel cell FC can be operated at a desired cell voltage.

From the cathode exhaust gas line L8,
The preheating line L20 is branched. This preheating line L
Reference numeral 20 branches off from the cathode exhaust gas line L8 on the downstream side of the pressure regulating valve PRV5. As shown in FIG. 1, a heat transfer tube T20 arranged in the water tank 21 of the water supply unit 20 is provided in the middle of the branch. Is provided. The water stored in the water tank 21 via the heat transfer tube T20 is supplied to the fuel cell F
Heat exchange is performed with the cathode exhaust gas discharged while the temperature is raised from C. This makes it possible to preheat water (reforming water and humidifying water) in the water tank 21 to a predetermined temperature (for example, about 80 ° C.) using the heat of the cathode exhaust gas. The preheating line L20 is connected to the reformer 30
Again before the evaporation section 31 of the cathode exhaust gas line L8
And the cathode exhaust gas that has passed through the water tank 21 of the water supply unit 20 as a heat source is reused as an oxidant by a burner provided in the evaporation unit 31.

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 maintained 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 1 is provided with a cooling system 60. 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. A further 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 stacking a large number of the separators SP and the single cells UC. . The flow path formed by the openings 56 and the flow path formed by the openings 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). Also, 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 60 includes a cooling medium circulation pump P3, a cooling medium line L9, and a cooling medium return line L1.
0, a radiator 6 including a heat exchanger 62 and a fan 63
1 and so on. That is, as shown in FIG. 1, the cooling medium circulation pump P3 is connected to the cooling medium inlet 49a of the fuel cell FC via the cooling medium line L9. A cooling medium return line L10 is connected to a cooling medium outlet 49b of the fuel cell FC, and the cooling medium return line L10 is connected to a refrigerant inlet RI of a heat exchanger 62 constituting the radiator 61. .

Therefore, when the cooling medium circulating pump P3 is operated, cooling water and the like are introduced into the cooling flow path 58 of the fuel cell FC through the cooling medium line L9 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 40 and the like is returned to the radiator 61 via the cooling medium outlet 49b and the cooling medium return line L10. The cooling water and the like are cooled by the radiator 61 and supplied to the fuel cell FC again by the cooling medium circulation pump P3. Thereby, the operating temperature of the fuel cell FC is always kept in a suitable range (for example, about 60 ° C. to 80 ° C.).

The cooling water or the like flowing through the cooling system 60 is also used as a cold heat source for cooling the fuel gas in the condenser 35. That is, from the cooling medium line L9,
The cooling medium line L11 is branched, and the cooling medium line L11 is connected to a heat transfer tube T35 constituting the condenser 35. Thereby, the cooling medium circulation pump P3
Is operated, the cooling water or the like is also supplied to the heat transfer tube T35 of the condenser 35. The cooling water or the like flowing through the heat transfer tube T35 is returned to the refrigerant inlet RI of the heat exchanger 62 constituting the radiator 61 via a pipe (not shown), and is used for cooling and cooling.
Recirculated.

Further, a cooling medium line L12 branches off from the cooling medium line L9. The cooling medium line L12 is connected to a fluid inlet of a heat transfer tube T32 arranged in the reforming section 32 of the reformer 30. It is connected. The fluid outlet of the heat transfer tube T32 is connected to the fluid inlet of the heat transfer tube T33 disposed in the selective oxidation section 33. Therefore, if the cooling medium circulation pump P3 is operated, the reforming unit 3
The cooling water or the like is also supplied to the second heat transfer tube T32 and the heat transfer tube T33 of the selective oxidation section 33. This makes it possible to remove excess heat of reaction generated inside the reforming section 32 and the selective oxidizing section 33 using the cooling water or the like flowing through the cooling system 60. The heat transfer tube T3 of the selective oxidation section 33
The cooling water or the like flowing through 3 is returned to the refrigerant inlet RI of the heat exchanger 62 constituting the radiator 61 via a pipe (not shown), and is cooled and recirculated.

In addition, a further cooling medium line L13 is branched from the cooling medium line L12, and cooling water and the like extracted through the cooling medium line L13 are discharged from the evaporating section 31 of the reformer 30. It is used to cool the exhaust gas discharged. That is, an exhaust gas line L14 for discharging the anode exhaust gas, the cathode exhaust gas and the like burned inside is connected to the evaporating section 31, and a heat exchanger 65 is provided on the exhaust gas line L14. The cooling medium line L13 branched from the cooling medium line L12 is connected to a fluid inlet of a heat transfer tube T65 constituting the heat exchanger 65. Thereby, the reformer 30
Is cooled by cooling water or the like flowing through the cooling system 60 and then discharged out of the system. The cooling water or the like flowing through the heat transfer tube T65 of the heat exchanger 65 is also supplied to the heat exchanger 62 forming the radiator 61 via a pipe (not shown).
Is returned to the refrigerant inlet RI, and is cooled and recirculated.

Here, in the fuel cell device 1 configured as described above, the electrolyte membrane EM (solid polymer electrolyte membrane) of each single cell UC is sufficiently humidified in order to stabilize the performance of the fuel cell FC. It is necessary. In view of this point, the fuel cell device 1 is configured to humidify air as a cathode reactant gas fed from a blower B as a cathode reactant gas supply unit and supply the humidified air to each cathode C of the fuel cell FC. It is configured.

For this reason, as shown in FIG. 1, an air supply line L6 connecting a blower B as a cathode reactant gas supply means and an air inlet 47b connected to each cathode C of the fuel cell FC is provided with: A humidifying shell 70 is provided. Thereby, the air pumped from the blower B passes through the inside of the humidifying shell 70 and then flows into the air inlet 47b of the fuel cell FC. Humidification shell 70,
It is configured as a closed container, and a nozzle N is connected to a side portion thereof. This nozzle N is connected to a humidifying water line L1 via an electromagnetic valve SV5 functioning as a flow rate adjusting means.
5 is connected to one end. As shown in FIG. 1, the other end of the humidification water line L15 is connected to a water pump P2 of the water supply unit 20.
Pressure adjustment line L between the pressure adjustment valve PRV2
Connected to P2.

As described above, the fluid pressure in the pressure adjustment line LP2 between the water pump P2 and the pressure adjustment valve PRV2 is kept constant by the pressure adjustment valve PRV2. Therefore, the inside of the humidification water line L15 is always filled with the water in the water tank 21, and the fluid pressure in the humidification water line L15 on the upstream side (the water supply unit 20 side) of the solenoid valve SV5 is always constant. As a result, the solenoid valve SV5
Is opened and closed intermittently, the water (humidifying water) flowing into the humidifying water line L15 from the water tank 21 is supplied to the nozzle N, and the humidifying water is supplied from the nozzle N serving as a water injection unit into the humidifying shell 70. Will be injected intermittently.
In addition, by using the water supply unit 20, which is a unit for supplying the reforming water to the reforming device 30, as a unit for supplying the water for humidification, the entire fuel cell device 1 can be further improved. It can be more compact.

Further, the heat transfer tube T7
0 is arranged. Then, from the cooling medium return line L10 of the cooling system 60, the refrigerant inlet RI of the heat exchanger 62 is provided.
A cooling medium line L16 is branched on the upstream side of the cooling medium line L16, and the cooling medium line L16 is connected to a fluid inlet of the heat transfer tube T70. Thereby, the stack 40 and the like are cooled to a predetermined temperature (for example, about 90 ° C. to 95 ° C.).
A part of the cooling water or the like flowing out of the cooling medium outlet 49b of the fuel cell FC does not return to the radiator 61 but flows into the heat transfer tube T70 arranged in the humidifying shell 70. Heat transfer tube T arranged in humidifying shell 70
A cooling medium return line L17 is connected to the fluid outlet 70, and the cooling medium return line L17 is connected to a suction port of the cooling medium circulation pump P3.

On the other hand, in the air supply line L6, a pressure regulating valve PRV6 is disposed downstream of the humidifying shell 70. The pressure regulating valve PRV6 always maintains the air pressure in the air supply line L6 at the outlet of the humidifying shell 70 at a predetermined value. Thus, the pressure of the fluid inside the humidifying shell 70 is always kept constant. Further, in the air supply line L6, a demister D is disposed downstream of the pressure regulating valve PRV6. This demister D
Is capable of removing water droplets (droplets) entrained by gas. The water collected by the demister D is returned to the water tank 21 of the water supply unit 20 and is reused for various uses.

As described above, in the fuel cell device 1, each line is connected to the fuel line L1, the reforming water line L2, the air lines L3, L4, and the nozzle N (humidifying water line L15). Electromagnetic valves SV1 to SV5 that can be opened and closed intermittently are provided. By adopting such a configuration, the fuel cell device 1 is significantly reduced in cost and size.

That is, the fuel supply unit 10 for supplying methanol to the reformer 30 is provided with a pressure regulating valve PRV1. The pressure regulating valve PRV1 discharges the fuel from the fuel pump P1 to pass through the pressure regulating line LP1. The pressure of the flowing fluid is kept constant. Therefore, methanol as fuel is always supplied from the fuel supply unit 10 to the inlet of the solenoid valve SV1 at a constant pressure. Similarly, the water supply unit 20 serving as a supply source of the reforming water and the humidifying water is provided with a pressure regulating valve PRV2.
2, the fluid pressure discharged from the water pump P2 and flowing through the pressure adjustment line LP2 is always kept constant. Therefore, reforming water is always supplied from the water supply unit 20 to the inlets of the solenoid valves SV2 and SV5 at a constant pressure. Further, from the blower B serving as a supply source of the reforming air, the reforming air is supplied to the inlets of the solenoid valves SV3 and SV4 at a constant pressure. Therefore, each of the solenoid valves SV1 to SV5
The fluid pressure at the inlet of is always constant.

On the other hand, in the fuel cell device 1, the reformer 30
The pressure of the fluid such as the mixed gas of water / methanol and the reformed gas inside is always kept constant by the pressure regulating valve PRV3. Similarly, the pressure of the fluid inside the humidifying shell 70 is always kept constant by the pressure regulating valve PRV6. Therefore, the fluid pressure at the outlets of the solenoid valves SV1 to SV5 is always constant.

As a result, in the fuel cell device 1, the differential pressure between the inlet and the outlet of each of the solenoid valves SV1 to SV5 is always kept constant. And each solenoid valve SV1
By keeping the differential pressure between the inlet and outlet of the SV5 constant, the flow characteristics in each of the lines L1, L2, L3, L4, and L15 are greatly simplified, and the differential pressure and the solenoid valves SV1 to SV1 are used. The supply amount of the fluid to the reformer 30 and the humidifying shell 70 can be extremely easily determined from the opening time of the SV5.

As described above, in the fuel cell device 1, while controlling the opening and closing of each of the solenoid valves SV1 to SV5 while keeping the differential pressure between the inlet and the outlet of each of the solenoid valves SV1 to SV5 constant, the reformer 30 And the humidifying shell 70 are intermittently supplied with the respective fluids. Thereby, the supply amount of the fluid to the reforming device 30 and the humidifying shell 70, that is, the supply amounts of the fuel (methanol), the reforming water, the reforming air, and the humidifying water are always optimally and accurately adjusted. Becomes possible.
As a result, it is not necessary to use a large and expensive thermal mass flow controller or the like as the flow path opening / closing means, and it is possible to employ small and inexpensive solenoid valves SV1 to SV5. Therefore, the entire fuel cell device 1 can be significantly reduced in cost and size.

Next, the specific structure of the solenoid valves SV1 to SV5 will be described with reference to FIG. Each of the solenoid valves SV1 to SV5 has the same configuration, and can be manufactured at extremely low cost and compact (for example, about 5 to 10 cm in total length). The solenoid valves SV1 to SV5 are shown in FIG.
As shown in FIG. 1, the valve body 80 has a substantially cylindrical shape. The valve body 80 has a valve inlet 81 at one end and a valve outlet 82 at the other end.
The valve outlet 82 is communicated with the valve outlet 82 by a flow path 83 extending straight.

A valve seat 84 is formed near a valve outlet 82 in a flow path 83 formed in the valve body 80.
In the flow path 83, a valve body 85 attached to a movable core 86 via a shaft is slidably disposed. The valve body 85 and the movable iron core 86 are urged against the valve seat 84 by urging means such as a spring (not shown).
The flow path 83 is closed by a valve seat 84 and a valve body 85. An electromagnetic coil 87 is arranged in the valve body 80 so as to cover the periphery of the flow path 83 and the movable core 86. As for the solenoid valve SV5 provided in the humidification water line L15 for supplying humidification water to the humidification shell 70, a nozzle N is disposed in a valve outlet 82 as shown in the drawing part of FIG. It is preferable to make This makes it possible to make the configuration around the humidifying shell 70 compact.

A drive voltage is supplied from a constant voltage power supply 88 to these solenoid valves SV1 to SV5. The constant voltage power supply 88 has a DC power supply and a constant voltage circuit (not shown), and stabilizes an unstable DC voltage generated by the DC power supply with the constant voltage circuit to generate a stable DC voltage. . As shown in FIGS. 5 and 6, one end of the electromagnetic coil 87 of each of the solenoid valves SV1 to SV5 is connected in parallel to the positive output terminal of the constant voltage power supply 88. On the other hand, the negative output terminal of the constant voltage power supply 88 is connected to the transistor Tr.
The other ends of the electromagnetic coils 87 included in the respective solenoid valves SV1 to SV5 are connected in parallel via 1, Tr2, Tr3, Tr4 and Tr5.

A bypass resistor R and a capacitor Co are provided on an electric line connecting each of the solenoid valves SV1 to SV5 and each of the transistors Tr1 to Tr5. The gates of the transistors Tr1 to Tr5 are connected to the pulse generators PG1, PG2, PG3, PG, respectively.
4, PG5 are connected. Each pulse generator PG1
To PG5 turn ON / O each transistor Tr1 to Tr5.
A pulse (pulse voltage) for FF is generated. Thereby, each transistor Tr1 to Tr5
Function as a switching element.

That is, each of the pulse generators PG1 to PG
5, the transistors Tr1 to Tr5
Is turned on, the electromagnetic coils 8 of the solenoid valves SV1 to SV5 are turned on.
7 is applied with a drive voltage. Thereby, the electromagnetic coil 87 is excited, and the valve body 85 moves up together with the movable iron core 86, so that the electromagnetic valves SV1 to SV5 are opened. On the other hand, when each of the transistors Tr1 to Tr5 is turned off by a pulse from each of the pulse generators PG1 to PG5, application of the drive voltage to the electromagnetic coil 87 of each of the solenoid valves SV1 to SV5 is released, and the movable iron core 86 and the valve body 85
And urging means against the valve seat 84,
The solenoid valves SV1 to SV5 are closed.

As described above, the pulse generators PG1 to PG
G5 generates a pulse for intermittently applying a drive voltage to the electromagnetic coil. The width and cycle of the pulse, that is, the opening time and closing time of each of the electromagnetic valves SV1 to SV5 are shown in FIG. 5 and the control device 90 shown in FIG. The control device 90, as shown in FIG.
It has U91, ROM92, and RAM93. CP
U91 is composed of a microprocessor or the like and performs various arithmetic processing. A program for control / arithmetic processing is stored in the ROM 92 in advance.
It 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. This input / output port 9
4 is connected to each of the pulse generators PG1 to PG5 and an air flow regulating valve FRV provided downstream of the blower B. Therefore, each of the pulse generators PG1 to PG
Various signals and the like generated by the arithmetic processing of the CPU 91 are supplied to the control valve 5 and the air flow regulating valve FRV via the input / output port 94. Further, a load setting means (not shown) for setting a load on the fuel cell FC is connected to the input / output port 94 of the control device 90, and a load request signal issued 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. The storage device 95 stores a table indicating the opening time and the closing time of the solenoid valve SV1 according to the load request for the fuel cell FC, and a table indicating each of the solenoid valves SV2 to SV2.
SV5 and data indicating a predetermined proportionality constant determined for the air flow regulating valve FRV are stored. These various data are stored in the CPU 9 receiving the load request signal.
Read to 1. Then, the CPU 91 generates a control signal to be sent to each of the pulse generators PG1 to PG5 and the air flow regulating valve FRV based on the load request signal.

The table showing the opening time and closing time of the solenoid valve SV1 according to the load request to the fuel cell FC, that is, the supply amount of methanol according to the load request, is as follows.
It can be determined based on theoretical calculated values, experimental values, and the like.
Also, the solenoid valves SV2 to SV5 and the air flow regulating valve F
The proportionality constant relating to RV is determined by the ratio between the supply amount of methanol determined by the opening time and the closing time of the solenoid valve SV1 and the supply amounts of reforming water, reforming air, and humidifying water.
V5 is obtained for each air flow control valve FRV. In addition, instead of storing such proportional constant data in the storage device 95, for each of the solenoid valves SV1 to SV5, data indicating an opening time and a closing time according to a load request for the fuel cell FC is created. For the air flow regulating valve FRV, data indicating an opening degree according to a load request for the fuel cell FC may be created, and these data may be stored in the storage device 95.

With the control device 90 constructed as described above, the solenoid valves SV1 to SV5 and the air flow regulating valve F
RV is reliably and accurately controlled. Therefore, the fuel line L1, the reforming water line L2, the air lines L3, L
4. Air supply line L6 and humidification water line L15
Thus, the fuel methanol, the air as the cathode reaction gas, the reforming water, the reforming air, and the humidifying water are supplied to each target device stably and accurately. In addition,
The control device 90 can also be configured as a sequencer.

Next, the operation of the above-described fuel cell device 1 will be described with reference to the flowchart shown in FIG.

When the operation of the fuel cell device 1 is started, a load request signal is given from a predetermined load setting means to the CPU 91 of the control device 90. CPU91
When receiving the load request signal (S10), based on the load request signal, the solenoid valve S stored in the storage device 95
An access is made to a table indicating the opening time and closing time of V1. Then, the CPU 91 selects, from the table,
Data corresponding to the load request for the fuel cell FC indicated by the load request signal is read, and connected to the solenoid valve SV1 based on data indicating the opening time and the closing time of the solenoid valve SV1 corresponding to the load request. Pulse generator P
A control signal to be sent to G1 is generated. Thus, by determining the opening time and the closing time of the solenoid valve SV1,
The supply amount of methanol according to the load request for the fuel cell FC is determined (S12).

In step S12, the amount of methanol supplied according to the load request for the fuel cell FC is determined.
The PU 91 then reads from the storage device 95 each solenoid valve SV2
To SV5 and data indicating a predetermined proportionality constant determined for the air flow regulating valve FRV. And
The CPU 91 multiplies the data by the data indicating the opening time and closing time of the solenoid valve SV1 corresponding to the load request read in S12, and sends the data to each of the pulse generators PG1 to PG5 and the air flow regulating valve FRV. Generate control signals. As a result, the air supplied through the air flow regulating valve FRV, the reforming water supplied through the solenoid valve SV2,
The supply amount of the reforming air supplied through the solenoid valves SV3 and SV4 and the supply amount of the humidification water supplied through the solenoid valve SV5 are determined so as to meet a load request for the fuel cell FC. (S14).

The CP that has performed the processing in S12 and S14
U91 is provided for each of the pulse generators PG1 to PG5.
A control signal indicating the opening time and closing time of each of the solenoid valves SV1 to SV5 according to the load request is sent to the air flow regulating valve FRV, and a control signal indicating the opening degree according to the load request is sent to the air flow regulating valve FRV (S16). ). The processing in S10 to S16 described above is repeated every time the CPU 91 of the control device 90 receives the load request signal.

The pulse generator P which has received the control signal generated by the CPU 91 from the controller 90 in S16.
G1 to PG4 send out pulses to the respective solenoid valves SV1 to SV4. As a result, a drive voltage is intermittently applied to each of the electromagnetic coils 87, and the lines L1 to L4 are intermittently opened and closed by the electromagnetic valves SV1 to SV4. Also,
The actuator of the air flow regulating valve FRV is a CPU 9
When the control signal is received from No. 1, the opening degree is changed so as to respond to the load request.

As a result, the amount of methanol and the amount of the reforming water according to the load demand are optimally and accurately supplied to the evaporator 31 of the reformer 30, and the reformer 32 and the selective oxidizer 33 are supplied.
The reforming air is supplied optimally and accurately with an amount corresponding to the load demand. 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 30 can always generate the anode reaction gas having a very low carbon monoxide concentration. Become. 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 supplied to the air inlet 47b via the humidifying shell 70 with high accuracy.

On the other hand, the pulse generator PG5 which has received the control signal from the CPU 91 sends a pulse to the solenoid valve SV5. As a result, the drive voltage is intermittently applied to the electromagnetic coil 87 of the solenoid valve SV5, and the humidification water line L15 is opened and closed intermittently by the solenoid valve SV5. Accordingly, the nozzle N provided in the humidifying shell 70 is heated at a predetermined temperature (for example, 80 ° C.) by the cathode exhaust gas discharged from the fuel cell FC via the heat transfer tube T20 in the water tank 21.
Humidification water preheated to about (° C) is intermittently supplied. As a result, the humidifying water is intermittently injected into the humidifying shell 70 from the nozzle N serving as a water injection unit.

As described above, the inside of the humidifying shell 70 is supplied from the blower B as the cathode reaction gas heated to a predetermined temperature (about 120 ° C.). Therefore, inside the humidification shell 70, the heated air and the mist of the fine humidification water sprayed from the nozzle N come into contact with each other and exchange heat. Further, since the heat transfer tube T70 through which the cooling water or the like for cooling the fuel cell FC flows is disposed in the humidification shell 70, the mist of the humidification water sprayed from the nozzle N flows through the heat transfer tube T70. The fuel cell FC is cooled to a predetermined temperature (for example, 90
(To about 95 ° C. to 95 ° C.).

As a result, the mist of the humidifying water removes heat from the air from the blower B and the cooling water from the fuel cell FC to elevate the temperature and evaporate. Heat to the mist of the fuel cell FC
(For example, about 60 ° C. to 80 ° C.). As a result, the mist of the humidifying water evaporates to become steam, flows out of the humidifying shell 70 with the cooled air, and is supplied to each cathode C of the fuel cell FC together with the air.

Here, in the fuel cell device 1, the proportionality constant for the solenoid valve SV5 among the data stored in the storage device 95 is, as described above, the load request for the fuel cell FC, that is, the load request. Is determined as a proportional constant with respect to the amount of air proportional to the amount of methanol according to the following formula, and is further determined so as to satisfy the following condition. That is, in the fuel cell device 1, the solenoid valve SV
The proportionality constant for 5 is based on fluctuations during operation such as the preheating condition of the water in the water tank 21 (the fluid temperature in the preheating line L20) and the temperature of the cooling medium flowing through the heat transfer tube T70 as the heat exchange means. Therefore, the partial pressure of the water vapor mixed in the air flowing out of the humidifying shell 70 is determined to be equal to or lower than the saturated water vapor pressure at the operating temperature of the fuel cell FC.

As a result, even if the load demand on the fuel cell FC changes and the operating temperature of the fuel cell FC changes, air as the cathode reaction gas having an appropriate humidity is always supplied to each cathode C of the fuel cell FC. Can be prevented, and it is possible to prevent a situation in which water stays in the cathode C and prevents the inflow of air. The humidifying shell 7 is connected to the air supply line L6 of the fuel cell device 1.
A demister D is provided between the fuel cell FC and the fuel cell FC (cathode C). Therefore, even if the mist of the humidifying water does not completely evaporate in the humidifying shell 70 and the mist (droplets) of the humidifying water mixes with the air flowing out of the humidifying shell 70, the humidifying water reaches the respective cathodes C of the fuel cell FC. Mist can be prevented from reaching. Thus, a situation in which water stays in the cathode C and hinders the inflow of air is very reliably prevented.

As described above, in the fuel cell device 1, the humidified electrolyte membrane EM of the fuel cell FC is utilized by utilizing the sensible heat of the air supplied to the respective cathodes C of the fuel cell FC in a heated state. The humidifying water is evaporated, and the generated water vapor is supplied to each cathode C of the fuel cell FC while being accompanied by air. This makes it possible to efficiently humidify the electrolyte membrane EM, and to prevent a situation in which water stays in the cathode C and prevents the inflow of air. As a result, in the fuel cell device 1, the output of the fuel cell FC can be easily and reliably stabilized. Further, the humidifying shell 70 may be prepared in a relatively small size, and the space required for a device for humidifying the electrolyte membrane EM can be reduced as compared with the conventional case. It is also possible to make the entire device 1 compact.

Further, in this fuel cell device 1, the water in the water tank 21 supplied as humidifying water is preheated by utilizing the heat of the cathode exhaust gas. The mist of the humidifying water injected into the humidifying shell 70 receives, in addition to the sensible heat of the air, heat such as cooling water for cooling the fuel cell FC from the heat transfer tube T70 as a heat exchange unit. ing.
Therefore, humidifying water (mist) is removed from the air in the humidifying shell 70.
It is possible to reduce the amount of heat of vaporization to be given to
The burden on the blower B for raising the temperature of the air can be reduced. Thereby, the blower B can be made compact, so that the whole fuel cell device 1 can be made compact.

It is extremely effective to flow cooling water or the like, which has been cooled by heating the fuel cell FC, through the heat transfer tube T70, which is a heat exchange means disposed in the humidifying shell 70, in the following points. It is. That is, if such a configuration is adopted, the cooling water or the like of the fuel cell FC, which has conventionally only been radiated by the radiator 61, is replaced with humidifying water (mist).
Can be effectively used as an auxiliary heat source for evaporating water, and the humidifying water can be reliably evaporated in the humidifying shell 70 to prevent the humidity of the air from becoming insufficient.

Further, the temperature of the cooling water or the like that has cooled the fuel cell FC is substantially equal to the operating temperature (for example, about 80 to 100 ° C.) of the fuel cell FC that changes according to a load change or the like. Therefore, if the cooling water or the like flows through the heat transfer tube T70, the temperature inside the humidifying shell 70 changes following the change in the operating temperature of the fuel cell FC, and the humidity of the air as the cathode reaction gas, that is, In addition, the amount of humidifying water evaporated in the humidifying shell 70 and mixed into the air can be made to follow the load fluctuation of the fuel cell FC.

In addition, in such a configuration, after cooling the fuel cell FC, the cooling water or the like that has passed through the humidifying shell as a heat source gives heat to the humidifying water (mist) to sufficiently lower the temperature. Will do. Therefore, cooling water or the like that has passed through the humidifying shell 70 after flowing through the fuel cell FC does not need to be radiated by the radiator 61. This allows
The radiator 61 for radiating the cooling water or the like can be significantly reduced in size. In this regard, such a configuration is extremely effective in making the entire fuel cell device 1 compact.

[0105]

As described above, the fuel cell device according to the present invention has a fluid supply means capable of supplying various fluids to the reformer at a substantially constant pressure, and a fluid pressure inside the reformer that is substantially equal to the fluid pressure. It is provided with a pressure regulating means for keeping the pressure constant, and a flow passage opening / closing means which is provided in a fluid line connecting the reformer and the fluid supply means and which can open / close the fluid line intermittently. In the method for operating the fuel cell device according to the present invention, the flow path opening / closing means is intermittently opened / closed while the difference between the fluid pressure at the inlet of the flow path opening / closing means and the fluid pressure inside the reformer is kept substantially constant. And a predetermined fluid is supplied to the reformer. This makes it possible to accurately supply fuel and the like to the reformer, and to easily reduce the cost and size of the fuel cell device.

[Brief description of the drawings]

FIG. 1 is a system diagram showing 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 schematic diagram for explaining a solenoid valve employed in the fuel cell device of FIG. 1;

FIG. 6 is a control block diagram of the fuel cell device shown in FIG.

FIG. 7 is a flowchart for explaining a control procedure of the fuel cell device shown in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel cell device, 10 ... Fuel supply part, 11 ... Fuel tank, 20 ... Water supply part, 21 ... Water tank, 30 ... Reforming device, 31 ... Evaporation part, 32 ... Reforming part, 33 ... Selective oxidation part ,
35: condenser, 40: stack, 41a: anode current collector, 41b: cathode current collector, 42: insulating plate, 43: stack tightening plate, 44a, 44b: flange, 45: membrane plate, 47a: fuel gas Inlet, 47b ... air inlet, 48a
... Anode exhaust gas outlet, 48b ... Cathode exhaust gas outlet,
49a: cooling medium inlet, 49b: cooling medium outlet, 50
a, 50b, 51a, 51b, 56, 57...
2, 53 groove, 54 fuel gas channel, 55 air channel,
58: cooling channel, 60: cooling system, 61: radiator,
65: heat exchanger, 70: humidified shell, 80: valve body, 8
1 ... valve inlet, 82 ... valve outlet, 83 ... flow path, 84 ... valve seat,
85 ... valve element, 86 ... movable iron core, 87 ... electromagnetic coil, 88
... constant voltage power supply device, 90 ... control device, 92 ... ROM, 9
3 RAM, 94 input / output port, 95 storage device, A
... Anode, B ... Blower, C ... Cathode, Co ... Condenser, D ... Demister, EM ... Electrolyte membrane, FC ... Fuel cell, FRV ... Air flow control valve, L1 ... Fuel line, L2
... reforming water line, L3, L4 ... air line, L5 ... fuel gas supply line, L6 ... air supply line, L7 ... anode exhaust gas line, L8 ... cathode exhaust gas line, L
9, L11, L12, L13, L16 ... cooling medium line, L10, L17 ... cooling medium return line, L14 ... exhaust gas line, L15 ... humidification water line, L20 preheating line, LP1, LP2 ... pressure adjustment line, LS ... fuel supply Line, N: nozzle, P1: fuel pump, P2: water pump, P3: cooling medium circulation pump, PG1, PG2, PG
3, PG4, PG5 ... pulse generator, PRV1, PR
V2, PRV3, PRV4, PRV5, PRV6: pressure regulating valve, R: resistance, RI: refrigerant inlet, UC: single cell, S
P: Separator, SV1, SV2, SV3, SV4, S
V5: solenoid valve, T32, T33, T35, T70: heat transfer tube, Tr1, Tr2, Tr3, Tr4, Tr5: transistor.

Continued on front page F term (reference) 3H106 DA07 DA23 DB02 DB12 DB23 DB32 DC02 DC17 DD03 EE48 FB24 GA30 KK12 5H026 AA06 5H027 AA06 BA01 BA09 BA10 BA16 CC06 KK52 MM12

Claims (8)

[Claims] A fuel cell having a polymer electrolyte sandwiched between an anode and a cathode, wherein the anode reaction gas generated by the reformer is supplied to the anode, and the cathode reaction gas is supplied from a cathode reaction gas supply means. A fuel cell device that supplies power to the cathode and generates power by an electrochemical reaction, a fluid supply unit capable of supplying the fluid to the reformer at a substantially constant pressure, and a fluid pressure inside the reformer. Pressure regulating means for keeping the pressure substantially constant, and a flow passage opening / closing means provided in a fluid line connecting the reformer and the fluid supply means, and capable of intermittently opening and closing the fluid line. Fuel cell device. 2. The pressure adjusting means is provided in a gas line for supplying an anode reaction gas from the reformer to the anode, and keeps a pressure of the anode reaction gas at an outlet of the reformer substantially constant. The fuel cell device according to claim 1, wherein 3. The control device according to claim 1, further comprising control means for setting a ratio between an opening time and a closing time of the flow path opening / closing means based on a load request for the fuel cell. Fuel cell device. 4. An electromagnetic valve, comprising: a movable iron core attached to a valve body that opens and closes a flow passage formed in a valve body; and an electromagnetic coil arranged to cover the movable iron core. The fuel cell device according to any one of claims 1 to 3, wherein 5. A fuel cell system comprising: a pulse generator for generating a pulse signal for intermittently applying a drive voltage to the flow channel opening / closing device; wherein the control device controls the flow channel in response to a load request for the fuel cell. 5. The fuel cell device according to claim 4, wherein an opening time and a closing time of the opening / closing means are determined, and a pulse signal corresponding to the opening time and the closing time is generated by the pulse generating means. 6. A fuel cell having a polymer electrolyte sandwiched between an anode and a cathode, wherein an anode reaction gas generated by a reformer is supplied to the anode and the cathode reaction gas is supplied from a cathode reaction gas supply means. In a method of operating a fuel cell device that supplies power to a cathode and generates power by an electrochemical reaction, a fluid line for supplying a predetermined fluid to the reformer is provided with a flow path opening / closing means, While maintaining the difference between the fluid pressure at the inlet and the fluid pressure inside the reformer substantially constant, the flow path opening / closing means is intermittently opened and closed to supply the predetermined fluid to the reformer. Operating method of the fuel cell device. 7. The fuel according to claim 6, wherein the fluid pressure inside the reformer is kept substantially constant by keeping the pressure of the anode reaction gas at the outlet of the reformer substantially constant. How to operate the battery device. 8. The operating method of a fuel cell device according to claim 6, wherein a supply duration time and a supply stop time of the fluid to the reformer are determined according to a load request for the fuel cell. .