JP2000357530A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the consumption amount of water by recovering water in exhaust gas. SOLUTION: In this fuel cell system 10, gaseous hydrogen from a gaseous hydrogen supply system 12 and air from an air supply line 13 are supplied to a solid polymer fuel cell 11 to generate power, and a full heat exchanger 47 capable of recovering heat and moisture in exhaust air within an exhaust air line 38 into air within the air supply line 13 is installed in the exhaust air line 38 in a gas exhaust system 30 for discharging exhaust gas from the fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system having a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In general, a polymer electrolyte fuel cell is constituted by stacking a plurality of cells (unit cells). Each cell has a solid polymer electrolyte membrane, a pair of electrodes (anode, cathode) arranged opposite to both sides of the solid polymer electrolyte membrane, and a gas flow path for supplying hydrogen gas to the anode. And a cathode substrate in which a gas flow path for supplying oxygen gas or air to the cathode is formed.

In each cell, hydrogen is oxidized at the anode to form protons (H ⁺ ), which move through the solid polymer electrolyte membrane to the cathode, where they are reduced by an electrochemical reaction. And turn into water.
Electricity (DC power) is generated with this electrochemical reaction.

In order for protons to move through the solid polymer electrolyte membrane, the solid polymer electrolyte membrane needs to be in a wet state with water, and if the wet state is insufficient,
The ionic conductivity of the solid polymer electrolyte membrane decreases, and the battery performance decreases.

In order to prevent this, a conventional polymer electrolyte fuel cell humidifies the polymer electrolyte membrane by directly supplying humidified water together with hydrogen gas to the gas flow path of the anode substrate. is there.

[0006]

However, in order to satisfactorily wet the solid polymer membrane of the fuel cell, it is necessary to sufficiently supply humidification water from a humidification water supply system.
A large amount of water as humidification water is consumed.

An object of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell system capable of collecting water in exhaust gas and reducing water consumption.

[0008]

According to the first aspect of the present invention, an anode gas from an anode gas supply system and a cathode gas from a cathode gas supply system are supplied to a fuel cell. In a fuel cell system in which a fuel cell generates electric power, heat and moisture of the exhaust gas in the gas exhaust system are supplied to a gas exhaust system for exhausting the exhaust gas from the fuel cell, and the anode side gas in the anode gas supply system. A total heat exchanger capable of recovering gas or the cathode side gas in the cathode side gas supply system is provided.

According to a second aspect of the present invention, an anode gas from an anode gas supply system, a cathode gas from a cathode gas supply system, and humidified water from a humidified water supply system are supplied to a fuel cell. In the fuel cell system in which the fuel cell generates electric power, a cooler capable of setting the temperature of the exhaust gas to a dew point or lower is disposed in a gas exhaust system for exhausting the exhaust gas from the fuel cell. The present invention is characterized in that the water contained therein is configured to be recoverable in the humidification water supply system.

According to a third aspect of the present invention, in the second aspect, the cooler is a cooler using a Peltier element.

[0011] The invention according to claim 4 is the invention according to claims 1 to 3.
In the invention described in any one of the above, the anode-side gas supply system is a hydrogen gas supply system that supplies hydrogen gas,
The cathode-side gas supply system is an air supply system that supplies air.

The invention according to claim 1 or 4 has the following operation.

The moisture of the exhaust gas in the gas discharge system is changed by the total heat exchanger into the anode gas (hydrogen gas) in the anode gas supply system (hydrogen gas supply system) or the cathode gas supply system (air supply system). , The amount of water discharged from the gas discharge system to the outside air decreases, and the amount of water consumed in the fuel cell system can be reduced.

Further, since the heat of the exhaust gas in the gas discharge system is recovered by the total heat exchanger to the anode gas in the anode gas supply system or the cathode gas in the cathode gas supply system, The temperature of the anode-side gas in the gas supply system or the temperature of the cathode-side gas in the cathode-side gas supply system rises, and the electrochemical reaction in the fuel cell can be efficiently performed, and therefore, the fuel cell operates with high efficiency. be able to.

The invention according to claim 2, 3 or 4 includes:
It has the following effects:

A cooler capable of setting the temperature of the exhaust gas below the dew point is disposed in the gas exhaust system for exhausting the exhaust gas from the fuel cell, and the moisture in the exhaust gas is recovered by the humidified water supply system. The amount of water discharged from the gas discharge system to the outside air is reduced, and the amount of water consumed in the fuel cell system can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. [A] First Embodiment (FIGS. 1 and 2) FIG. 1 is a configuration diagram showing a first embodiment of a fuel cell system according to the present invention.

The polymer electrolyte fuel cell system 10 shown in FIG. 1 includes a polymer electrolyte fuel cell 11, a hydrogen gas supply system 12 as an anode gas supply system, and an air supply system 13 as a cathode gas supply system. , A humidification water supply system 14, a gas discharge system 30, a power output system 31, and a control device 15, and the polymer electrolyte fuel cell 11 generates electricity (DC power).

The polymer electrolyte fuel cell 11 is configured as a module by stacking a plurality of cells 16 (single cells) shown in FIG. Each cell 16 is arranged in contact with a solid polymer electrolyte membrane 17 such as a polymer ion exchange membrane, an anode 18 and a cathode 19 which are respectively joined to opposing surfaces of the solid polymer electrolyte membrane 17. It has an anode base material 20 and a cathode base material 21 arranged in contact with the cathode 19.

The anode 18 and the cathode 19 are mainly composed of carbon carrying platinum and have a diffusion path through which gas or water can diffuse. In the anode 18 and the cathode 19, an electrochemical reaction described below is performed.

The anode substrate 20 is provided with an anode gas passage 22 for flowing hydrogen gas as an anode gas on the side in contact with the anode 18. In the cathode base material 21, a cathode-side gas flow path 23 for flowing air (or oxygen gas) as a cathode-side gas is formed on the side in contact with the cathode 19. The anode substrate 20 and the cathode substrate 21 are formed of a porous material such as a carbon material, and are configured to be permeable to gas or water.

In the cell 16 configured as described above,
The hydrogen gas introduced into the anode 18 through the anode-side gas flow path 22 of the anode substrate 20
The protons are oxidized to form protons (H ⁺ ), which move through the solid polymer electrolyte membrane 17 and become
In the cathode 19, it is reduced by an electrochemical reaction with oxygen in the air introduced through the cathode-side gas flow passage 23 of the cathode substrate 21, and changes to water. With this electrochemical reaction, DC power is generated between the anode 18 and the cathode 19.

The hydrogen gas supply system 12 includes a hydrogen cylinder 2
4. The on-off valve 32, the pressure reducing valve 25, and the hydrogen supply electromagnetic valve 26 are sequentially arranged, and the hydrogen supply electromagnetic valve 26 is connected to the polymer electrolyte fuel cell 11. This hydrogen gas supply system 1
The hydrogen gas is supplied to the anode-side gas flow path 22 of the anode substrate 20 in each cell 16 of the polymer electrolyte fuel cell 11 by opening the on-off valve 32 and the hydrogen supply electromagnetic valve 26 in 2. This hydrogen gas is supplied to the hydrogen gas pressure reduced by the pressure reducing valve 25 and the throttle valve 39 of the gas discharge system 30.
The supply flow rate to the polymer electrolyte fuel cell 11 is adjusted by the valve opening degree (described later).

The air supply system 13 includes an air supply fan 2
7 is connected to the polymer electrolyte fuel cell 11. By adjusting the rotation speed of the air supply fan 27, the heat and humidity components are supplied to the cathode-side gas flow path 23 of the cathode substrate 21 in each cell 16 of the polymer electrolyte fuel cell 11 by the total heat exchanger 47 as described later. The air from which (moisture) has been collected is supplied at an appropriate flow rate.

In the humidification water supply system 14, a circulation pump 29 connected to a main water tank 28 and the main water tank 28 are connected to the polymer electrolyte fuel cell 11, and a water supply solenoid valve 33 is connected to the main water tank 28. , A water supply pump 34 and a sub water tank 35 are sequentially connected. In each of the cells 16 of the polymer electrolyte fuel cell 11, in order for protons (H ⁺ ) to move inside the polymer electrolyte membrane 17,
The solid polymer electrolyte membrane 17 needs to be wet by water. The humidification water supply system 14 includes the main water tank 2
The humidified water in the fuel cell 8 is directly supplied from the circulation pump 29 to the anode-side gas flow path 22 of the anode substrate 20 in each cell 16 of the polymer electrolyte fuel cell 11, and the humidified water is allowed to pass through the anode 18 to be solidified. To the polymer electrolyte membrane 17,
The solid polymer electrolyte membrane 17 is humidified and maintained in a good wet state.

The main water tank 28 supplies water generated at the cathode 19, which is diffused and permeated through the cathode substrate 21 in each cell 16 of the polymer electrolyte fuel cell 11, and to the polymer electrolyte membrane 17. Collect excess humidified water. The main water tank 28 collects water that has been reversely diffused from the cathode 19 of the polymer electrolyte fuel cell 11 to the anode 18 via the polymer electrolyte membrane 17 and has passed through the anode substrate 20. Further, when the water stored in the main water tank 28 becomes insufficient in the main water tank 28, the water supply solenoid valve 33 is opened, the water supply pump 34 is operated, and the water in the sub water tank 35 is Water is replenished. Water collected in the main water tank 28 and the sub water tank 35
Is supplied by the circulation pump 29,
As described above, the humidification water and the cooling water are directly supplied to the anode-side gas flow path 22 of each cell 16.

Reference numeral 36 denotes an opening operation when the fuel cell system 10 is maintained or the like.
8 is a drain cock for discharging the water in 8.

The gas discharge system 30 has an unused hydrogen gas discharge line 37 and a discharge air line 38. The unused hydrogen gas discharge line 37 has one end connected to the outlet of the anode 18 of the polymer electrolyte fuel cell 11, the main hydrogen tank 28 and the throttle valve 39, and the other end connected to the exhaust duct 40. Also, the exhaust air line 38
Has one end connected to the cathode 19 outlet of the polymer electrolyte fuel cell 11 and the other end connected to the exhaust duct 40. Further, the exhaust air line 38 includes an exhaust fan 41.

A small amount of unused hydrogen gas not subjected to the reaction in the polymer electrolyte fuel cell 11 flows through the unused hydrogen gas discharge line 37 from the anode 18 of the polymer electrolyte fuel cell 11 and It is guided to the exhaust duct 40 via the tank 28 and the throttle valve 39. In addition, the air whose oxygen has been consumed in the polymer electrolyte fuel cell 11 becomes exhaust air,
Further, a large amount of water generated in the polymer electrolyte fuel cell 11 is included as water vapor. The exhaust air flows from the cathode 19 of the polymer electrolyte fuel cell 11 through the exhaust air line 38 and is introduced into the exhaust duct 40. Unused hydrogen gas introduced into the exhaust duct 40 by the unused hydrogen gas discharge line 37 is discharged by the exhaust air line 38 into the exhaust duct 40.
The exhaust air guided to the inside and the air (outside air) introduced into the exhaust duct 40 by the exhaust fan 41 are mixed and diluted, and are discharged from the exhaust duct 40 into the outside air.

The power output system 31 includes a DC / AC inverter 42, a DC / DC converter 43, a charging circuit 44, and a charger 45.

The DC / AC inverter 42 controls the DC power (24 to 50 V) generated in the polymer electrolyte fuel cell 11.
Is converted into AC power (for example, 100 V) and can be output to the output terminal 48. This DC / AC inverter 42 can convert the frequency of the AC power to be converted into 50 Hz and 60 Hz. The DC / DC converter 43 converts the DC power generated in the polymer electrolyte fuel cell 11 into a DC power of a predetermined voltage (for example, 24 V).
9, water supply pump 34, air supply fan 27, exhaust fan 41, pressure reducing valve 25, hydrogen supply solenoid valve 26, water supply solenoid valve 3
3 and the accessory parts such as the throttle valve 39, the control device 15, and the charging circuit 44. This charging circuit 44 has a DC / D
The DC power supplied by the C converter 43 is
6 can be charged.

The charger 45 includes a secondary battery 46.
Is charged not by using the DC power from the DC / DC converter 43 but by using commercial AC power (for example, 100 V).

The control device 15 controls the fuel cell system 1
0 various controls are performed. That is, the control device 15 includes the polymer electrolyte fuel cell 11, the pressure reducing valve 25, the hydrogen supply electromagnetic valve 26, the air supply fan 27, the circulation pump 29, the water supply electromagnetic valve 33, the water supply pump 34, the throttle valve 39, and the exhaust fan 4
1. An electric signal is transmitted and received between the DC / AC inverter 42 and the DC / DC converter 43 to control these various devices. For example, when the control device 15 receives an abnormal signal from the polymer electrolyte fuel cell 11, the control device 15 closes the hydrogen supply electromagnetic valve 26 to perform the closing operation.
The supply of hydrogen gas to 1 is stopped, and the operation of the polymer electrolyte fuel cell 11 is stopped.

Now, a total heat exchanger 47 is disposed in the exhaust air line 38 of the gas exhaust system 30. The total heat exchanger 47 recovers heat and humidity (moisture) in the exhaust air flowing through the exhaust air line 38 into air flowing upstream of the air supply fan 27 in the air supply system 13. The exhaust fan 41 is connected to an exhaust air line 38 between the total heat exchanger 47 and the exhaust duct 40.

Therefore, according to the above embodiment, the following effects and advantages can be obtained.

Since the moisture in the exhaust air in the exhaust air line 38 in the gas exhaust system 30 is recovered into the air in the air supply system 13 by the total heat exchanger 47, the moisture is exhausted to the outside air via the exhaust duct 40. As the water content decreases, the water consumption in the fuel cell system 10 can be reduced.

Since the heat of the exhaust air in the exhaust air line 38 in the gas exhaust system 30 is recovered to the air in the air supply system 13 by the total heat exchanger 47, the temperature of the air in the air supply system 13 Is increased, and the electrochemical reaction in the polymer electrolyte fuel cell 11 can be efficiently performed, so that the polymer electrolyte fuel cell 11 can be operated with high efficiency.

[B] Second Embodiment (FIG. 3) FIG. 3 is a configuration diagram showing a second embodiment of the fuel cell system according to the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the fuel cell system 50 according to the second embodiment, the total heat exchanger 47 is not provided in the exhaust air line 38 of the gas exhaust system 30 and the cooler 51 is provided in the exhaust duct 40 of the gas exhaust system 30. And a water recovery line 52 is installed between the exhaust duct 40 and the water supply pump 34 of the humidification water supply system 14.

The cooler 51 is provided with a DC power output system 31.
The exhaust air and unused hydrogen gas (mainly exhaust air) in the exhaust duct 40 are set to a temperature equal to or lower than the dew point by the Peltier element operated by the DC power output from the / DC converter 43, and the exhaust air and the unused air are set. Dew condensation of moisture in hydrogen gas (mainly exhaust air). The condensed discharged air and the moisture in the unused hydrogen gas are collected in the main water tank 28 of the humidified water supply system 14 via the water collection line 52 while the water supply pump 34 is operating.

The water recovery line 52 includes a filtration device 53
Are arranged. The filtering device 53 removes debris in water discharged from the exhaust duct 40 by dew condensation with a filter, and removes ions with an ion exchange resin.

Therefore, according to the above embodiment, the following effects can be obtained.

The temperature of the discharged air and the unused hydrogen gas (mainly the discharged air) is set to the dew point or lower in the exhaust duct 40 of the gas exhaust system 30 for discharging the exhaust air and unused hydrogen gas from the polymer electrolyte fuel cell 11. A cooler 51 that can be set at the main water tank 28 of the humidified water supply system 14 is provided.
Therefore, the amount of water discharged to the outside air via the exhaust duct 40 is reduced, and the amount of water consumed in the fuel cell system 10 can be reduced.

Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

For example, as a modification of the first embodiment, the total heat exchanger 47 converts the heat and humidity (moisture) in the exhaust air flowing through the exhaust air line 38 into the hydrogen gas supply system 1.
In 2, the hydrogen gas flowing downstream of the hydrogen supply solenoid valve 26 may be recovered.

Further, in the first embodiment, the total heat exchanger 47 is disposed in the unused hydrogen gas discharge line 37 in the gas discharge system 30 and the unused hydrogen gas discharge line 3
Heat and humidity (moisture) in unused hydrogen gas flowing in 7
May be recovered to air flowing in the air supply system 13 on the upstream side of the air supply fan 27 or hydrogen gas flowing in the hydrogen gas supply system 12 on the downstream side of the hydrogen supply solenoid valve 26.

Further, the cooler 51 of the second embodiment is used.
Is not limited to the one using the Peltier element, but may be a heat exchanger that cools the exhaust air and unused hydrogen gas in the exhaust duct 40 with air or water.

[0048]

As described above, according to the fuel cell system according to the first aspect of the present invention, the heat and moisture of the exhaust gas in the gas exhaust system are supplied to the gas exhaust system for exhausting the exhaust gas from the fuel cell. Since a total heat exchanger capable of recovering the anode gas in the anode gas supply system or the cathode gas in the cathode gas supply system is installed, the water and heat in the exhaust gas are recovered to recover water. While reducing consumption,
The fuel cell can be operated with high efficiency. In particular, at the time of startup under a low outside air temperature, the battery temperature can be quickly raised, and the startability of the fuel cell can be improved.

According to the fuel cell system according to the second aspect of the present invention, a cooler capable of setting the temperature of the exhaust gas to a dew point or lower is arranged in the gas exhaust system for exhausting the exhaust gas from the fuel cell. Since the water in the exhaust gas can be recovered in the humidified water supply system, the water in the exhaust gas can be recovered and the water consumption can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing the configuration of the fuel cell of FIG. 1;

FIG. 3 is a configuration diagram of a second embodiment of the fuel cell system according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 fuel cell system 11 polymer electrolyte fuel cell 12 hydrogen gas supply system (anode side gas supply system) 13 air supply system (cathode side gas supply system) 14 humidified water supply system 30 gas discharge system 37 unused hydrogen gas discharge line 38 Exhaust air line 47 Total heat exchanger 50 Fuel cell system 51 Cooler 52 Water recovery line

Continuation of the front page (72) Inventor Shoichi Yoshida 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Shoji Tsunekawa 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka No. Sanyo Electric Co., Ltd. (72) Inventor Takashi Arai 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term within Sanyo Electric Co., Ltd. 5H026 AA06 CC03 5H027 AA06 BA13 DD03

Claims (4)

[Claims] 1. A fuel cell system in which an anode gas from an anode gas supply system and a cathode gas from a cathode gas supply system are supplied to a fuel cell, and the fuel cell generates electric power. The heat and moisture of the exhaust gas in the gas exhaust system are supplied to the gas exhaust system for exhausting the exhaust gas from the fuel cell by the anode side gas in the anode side gas supply system or the cathode side in the cathode side gas supply system. A fuel cell system comprising a total heat exchanger capable of recovering gas. 2. An anode-side gas from an anode-side gas supply system, a cathode-side gas from a cathode-side gas supply system, and humidification water from a humidification water supply system are supplied to a fuel cell. In a fuel cell system that generates electric power, a cooler capable of setting the temperature of the exhaust gas to a dew point or lower is disposed in a gas exhaust system that exhausts the exhaust gas from the fuel cell, and the moisture in the exhaust gas reduces the humidification water. A fuel cell system configured to be recoverable in a supply system. 3. The fuel cell system according to claim 2, wherein the cooler is a cooler using a Peltier element. 4. The system according to claim 1, wherein the anode-side gas supply system is a hydrogen gas supply system for supplying hydrogen gas, and the cathode-side gas supply system is an air supply system for supplying air. 4. The fuel cell system according to any one of claims 1 to 3.