JPH07192743A - Fuel cell power generating system - Google Patents

Abstract

PURPOSE:To adapt to environment for an automobile by arranging a hydrogen storage alloy and a solid polymer electrolyte fuel cell and independently connecting a cooling water line and a humidifying water line to the fuel cell. CONSTITUTION:A fuel cell 50 has ports 50a-50h, of which a pair of ports 50a, 50b are connected to a hydrogen gas line L10, hydrogen gas serving as fuel is introduced from the port 50a, and the remaining hydrogen is exhausted from the port 50b. A pair of ports 50c, 50d are connected to an air line L20, air serving as an oxidizing agent is introduced from the port 50c and the remaining air containing reaction water is exhausted from the port 50d. A pair of ports 50e, 50f are connected to a cooling water line L30, cooling water is introduced from the port 50e, and exhausted from the port 50f. A pair of ports 50g, 50h are connected to a humidifying water line L40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator, and more particularly to a mobile fuel cell, especially a vehicle fuel cell.

[0002]

2. Description of the Related Art Recently, electric vehicles have been drawing attention to environmental problems, that is, air pollution, and electric vehicles equipped with a storage battery have already been put into practical use. However, battery-powered vehicles have difficult problems to solve, such as a relatively short mileage and a long charging time due to the storage capacity of the battery. The advent of battery-powered vehicles is awaited (Japanese Patent Laid-Open No. 2-168).
803).

As a fuel cell power generator suitable for an electric vehicle, a phosphoric acid type or the like has been considered as disclosed in Japanese Patent Application Laid-Open No. 2-170369, but in view of future development, the outflow of liquid electrolyte is considered. From the viewpoint of avoidance, it seems desirable to adopt a solid polymer electrolyte fuel cell. FIG. 5 shows an overall outline of a conventional general system of a solid polymer electrolyte fuel cell. In the figure, reference numeral 1 is a low temperature operation type using hydrogen ion conductor, that is, 10
1 shows a solid oxide fuel cell operating below 0 ° C. Also,
Reference numeral 2 indicates a fuel tank provided with a hydrogen storage alloy as a hydrogen gas source. Here, the hydrogen storage alloy is already known as a hydrogen gas storage means for a fuel cell for a vehicle, as disclosed in Japanese Patent Laid-Open No. 170369/1990. In this hydrogen storage alloy, the hydrogen gas releasing reaction is an endothermic reaction,
It requires a heat source to maintain the gas pressure required by the fuel cell.

The fuel cell system A shown in FIG. 1 will be briefly described. The system A has a fuel system L1 and the hydrogen gas in the hydrogen storage alloy tank 2 is provided with a solenoid valve 3 and a pressure adjusting valve 4. It is supplied to the fuel cell 1 through the hydrogen supply pipe 5. As will be described later, the supplied hydrogen gas is humidified in the fuel cell 1 to a humidity of 100%, and then a necessary amount is supplied to the reaction, and the surplus hydrogen gas is naturally cooled after leaving the fuel cell 1. And the temperature of the condensed water decreases.
It is stored in the liquid separator 6. The hydrogen gas in the separator 6 is recirculated to the hydrogen supply pipe 5 by the pump 7, but in order to remove the ions eluted in the hydrogen due to a slight corrosion of the piping material during the passage of the hydrogen gas through the piping. First, the ion component in the wet hydrogen is removed through the deionization filter 8 while the hydrogen gas is being returned to the supply pipe 5.

Air as an oxidant is supplied to the fuel cell 1 through an air system L2. That is, the air pressurized by the air compressor 9 is supplied to the fuel cell 1 under a predetermined pressure via the buffer tank 10 and the pressure adjusting valve 11. In the figure, reference numeral 12 is a deionization filter. The air supplied to the fuel cell 1 is humidified in the fuel cell 1 and is used for reaction, and the surplus air is discharged to the outside together with reaction water (H ₂ O). The air (exhaust gas) exiting the fuel cell 1 is
After dehumidifying with the condenser 13, it is discharged to the outside of the system under the flow rate control by the throttle valve 14. Reference numeral 15 is a silencer.

The cooling water circulation system L3 for the fuel cell 1 is constituted by an independent path from the cooling water circulation system L4 for the hydrogen storage alloy 2. The circulation system L3 for the fuel cell is the water storage tank 1
7, the water storage tank 17 has the condenser 1 described above.
The water in 3 is supplied, that is, the water trapped by the air system L2. The water in the water storage tank 17 is pumped to the fuel cell 1 by the pump 18 for cooling the fuel cell 1 and humidifying the gas in the fuel cell 1 (these will be described later in detail). The L3 has a three-way valve 19 controlled in accordance with the temperature of the cooling water in the middle thereof.
By means of 9, the forced heat dissipation path passing through the radiator 20 is set when the temperature of the cooling water is higher than the predetermined temperature.
In the figure, reference numeral 21 is a fan. Before the cooling water enters the fuel cell 1, the deionization filter 22 removes dissolved ions.

FIG. 6 schematically shows the internal structure of a conventional fuel cell 1. The fuel cell 1 has two partitioned regions, that is, a reaction zone, that is, a power generation zone 25, and a humidification zone 26 in which a semipermeable membrane of water is stretched. The figure also shows the flow path of the cooling water in the fuel cell 1. The cooling water entering the fuel cell 1 from the inlet port 1a first passes through the power generation zone 25 to cool the fuel cell 1. After that, the process proceeds to the humidification zone 26, and thereafter, it is discharged from the outlet port 1b to the outside. By the cooling water that passes through the power generation zone 25 and then moves to the humidification zone 26, the cooling water that passes through the humidification zone 26 has a temperature and pressure of the cooling water in the power generation zone 25 that are substantially equal to each other, and the saturated water vapor amount is added to the gas. give.

FIG. 7 shows a flow path of hydrogen gas in the fuel cell 1, and FIG. 8 shows a flow path of air. Hydrogen gas and air first enter the humidification zone 26 through the inlet port 1c or 1e, and after receiving moisture from the cooling water in the humidification zone 26, move to the power generation zone 25 and react. Then, the surplus gas is discharged to the outside through the outlet port 1d or 1f.

[0009]

In developing a fuel cell type vehicle, it is needless to say that the cost of the fuel cell power generation system is reduced, but it is necessary to make the entire system compatible with the application environment for automobiles. Looking at the conventional system from such a viewpoint, the cooling water passing through the cooling water circulation system L3 serves as a refrigerant for cooling the fuel cell 1 and also serves as a humidifying water for humidifying the gas in the fuel cell 1. Has the role of. By the way, the fuel cell 1 does not like metal ions. Therefore, as a piping material forming the circulation system L3, a material that does not elute ionic components as much as possible, for example, a stainless material is used. The same applies to the radiator 20, and even if the heat exchange performance is poor, a radiator made of a stainless material is used. Further, since the cooling water itself is pure water, when the outside air temperature falls below zero, the fuel cell 1
The cooling water may freeze inside. Therefore, an object of the present invention is to provide a fuel cell power generation device adapted to an application environment for automobiles.

[0010]

In order to achieve the above technical object, according to the present invention, basically, a hydrogen storage alloy as a hydrogen gas source and a hydrogen gas as a fuel from the hydrogen storage alloy are used. A solid polymer electrolyte fuel cell for generating power by receiving the supply of a cooling water system for cooling the fuel cell and a humidification water system for humidifying the gas supplied to the fuel cell,
Each of them is independently connected to the fuel cell.

[0011]

According to the present invention, since the cooling water system for cooling the fuel cell and the humidifying water system for humidifying the gas in the fuel cell are separately configured, the cooling water flowing through the cooling water system is metal ions. Even if it contains, it does not harm the fuel cell, and therefore the cooling water is not limited to pure water as in the conventional case. From this, it is possible to give a degree of freedom to the selection of the piping material of the cooling water system or the material of the radiator, and it is possible to freely select the material suitable for the automobile. Further, since the degree of freedom in selecting the cooling water can be given, it is possible to prevent freezing in a cold region by using an antifreezing solution. Other objects and advantages of the present invention will become apparent from the description of the embodiments detailed below.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral B indicates
A fuel cell power generator for a vehicle is shown, and reference numeral 50 is a solid oxide fuel cell. The fuel cell 50 has a port 50a
.About.50h, and of these ports, the paired ports 50a and 50b are connected to the hydrogen gas system L10, hydrogen gas as a fuel is introduced from the port 50a, and surplus hydrogen is discharged from the port 50b. The pair of ports 50c and 50d are connected to the air system L20, and
Air as an oxidant is introduced from c, and excess air containing reaction water is discharged from the port 50d. The pair of ports 50e and 50f are connected to the cooling water system L30, the cooling water is introduced from the port 50e, and is discharged from the port 50f. The paired ports 50g and 50h are connected to a humidifying water system L40 which will be described in detail later.

The hydrogen gas system L10 has a tank 51 containing a hydrogen storage alloy as a hydrogen gas source. here,
As the hydrogen storage alloy, a so-called high temperature type hydrogen storage alloy that releases hydrogen gas at about 60 to 80 ° C. is adopted. The hydrogen tank 51 and the inlet port 50a are connected to each other via a hydrogen supply pipe 52. The supply pipe 52 has a solenoid opening / closing valve 5 in order from the tank 51 side toward the fuel cell 50 side.
3, pressure regulating valve 54, pump 55, deionization filter 5
6 is interposed. The outlet port 50b is connected to the gas / liquid separator 58 via the hydrogen discharge pipe 57, and the discharge pipe 57
A check valve 59 is installed in the. Also, hydrogen gas system L
10 is a supply pipe 52 for supplying the hydrogen gas separated by the separator 58.
It has a hydrogen reflux pipe 60 for returning to. That is, the reflux pipe 60
Has its upstream end connected to the separator 58 and its downstream end connected to the hydrogen supply pipe 52, specifically, to the suction side portion of the pump 55. A relief valve 61 having an atmospheric pressure as a reference pressure is interposed in the hydrogen recirculation pipe 60 so that the pressure of the hydrogen gas in the fuel cell 50 is substantially equal to that of the relief valve 6.
1 and also the relief valve 61 and the separator 5
An exhaust pipe 64 equipped with a solenoid type on-off valve 62 and a silencer 63 is connected between the exhaust pipe 64 and the solenoid 8.

The air system L20 has an air supply pipe 65 connected to the air introduction port 50c and an exhaust pipe 66 connected to the air discharge port 50d. The supply pipe 65 has an air compressor 67, a check valve 68, a buffer tank 69, and a pressure adjusting valve 7 in that order from the upstream end thereof toward the fuel cell 50.
0, a deionization filter 71 is provided. The air compressor 67 is driven by the electric motor 72, and the pressurized air discharged from the compressor 67 is stored in the tank 69 and the pressure adjusting valve 7.
The fuel cell 5 is adjusted to a predetermined pressure under the pressure control of 0.
Supplied to zero. On the other hand, the exhaust pipe 66 has a fuel cell 50
From the downstream end to the condenser 73 and the throttle 7 in that order.
4. A silencer 75 is provided, and excess air (including reaction water) discharged from the port 50d is released to the atmosphere after the water content is removed by the condenser 73. On the other hand, the water separated in the condenser 73 is stored in the water storage tank 77 through the pipe 76. The wall of the water storage tank 77 is covered with a heat insulating material 77a.

The cooling water system L30 is configured so that the fuel cell 50 and the hydrogen storage alloy tank 51 are used in common. That is, the inlet port 51a of the tank 51 and the outlet port 50f of the fuel cell 50 are connected by the first pipe 80 for cooling water. Further, the inlet port 50e of the fuel cell 50 and the outlet port 51b of the tank 51 are connected to each other by the second pipe 8 for cooling water.
1 is connected. A pump 82 is provided in the first pipe 80, while a radiator 84 having an electric fan 83 and a bypass pipe 85 that bypasses the radiator 84 are provided in the second pipe 81. 85
Has its upstream end connected to the second pipe 81 via a three-way valve 86.

The humidifying water system L40 includes a first pipe 90 connecting the port 50g of the fuel cell 50 and the water storage tank 77,
Deionization filter 91 interposed in the first tube 90
And a pressure accumulation tank 93 connected to the port 50h of the fuel cell 50 through the second pipe 92. The pressure accumulation tank 93 is filled with, for example, an inert gas or air 93a. Here, the amount of the inert gas 93a sealed in the accumulator tank 93 depends on the inert gas or the gas pressure of the air 93a when the fuel cell 50 is not operating. Humidification water in the first
The amount is sufficient to push it back into the pipe 90 or the water storage tank 77. On the other hand, when the fuel cell 50 is in the operating state, the pure water in the water storage tank 77 is pushed into the fuel cell 50 and the accumulator tank 93 by the pressure of the pressurized air passing through the exhaust pipe 66, and the pure water in the accumulator tank 93 is stored. The pressure and the pressure in the water storage tank 77 (pressure of the pressurized air) are maintained in a balanced state. The humidifying water system L40 and the air system L20 are connected to each other via a water guiding pipe 94, one end of which is connected to the separator 58 and the other end of which is connected to the condenser 73. The check valve 96 is interposed. As will be described later, the water pipe 94 is not limited to the condenser 73 as a connection point for the air system L20, and the exhaust port 66 of the fuel cell 50 in the exhaust pipe 66 is not limited to the condenser 73.
And the condenser 73 may be connected.

The internal structure of the fuel cell 50 is divided into a reaction zone, that is, a power generation zone 97 and a humidification zone 98, as in the conventional case, and the cooling water passes through the power generation zone 97 as shown in FIG. After that, it moves to the humidification zone 98 and then discharged to the outside. On the other hand, as shown in FIG. 3, the humidifying water goes directly to the humidifying zone 98 without passing through the power generation zone 97.
Here, the structure of the humidification zone 98 is as shown in FIG.
As a unit unit, a pair of water semipermeable membranes 99a and 99b are provided with the cooling water passage 98a interposed therebetween.
Alternatively, the air passage 98b and the first humidification water passage 98c or the hydrogen gas passage 98d and the second humidification water passage 9 are sandwiched with 99b interposed therebetween.
8e is formed, and the first humidification water passage 98c and the second humidification water passage 98e are arranged adjacent to the cooling water passage 98a. Reference numeral 100 in FIG. 1 is a level sensor for detecting the water level, and the water level detected by the sensor 100 is sent to a control unit (C / U) (not shown) and used for controlling various valves and the like.

With the above structure, first, the cooling water system L30
Since the humidifying water system L40 and the humidifying water system L40 are independently configured, it is possible to reduce the amount of humidifying water supplied to the fuel cell 50, that is, the amount of water required to maintain the deionized state, as compared with the conventional case. According to this embodiment, there are the following advantages. Cooling water system for fuel cell 50 and hydrogen storage alloy tank 5
The cooling water system for 1 can be integrated as in the embodiment. This also means that the exhaust heat of the fuel cell 50 can be used to heat the hydrogen storage alloy to accelerate the release of hydrogen gas. Incidentally, in the past, the hydrogen storage alloy tank 51 was formed of an aluminum alloy material in order to reduce the weight, but the aluminum material is liable to be eluted as ions in water, and the water containing the ions is used as a gas for the fuel cell 50. It is considered that the cooling water system for the tank 51 and the cooling water system (including the humidifying water) for the fuel cell 50 cannot be integrated because the hydrogen ion conductivity of the ion exchange membrane is impaired when the above humidification is performed. It was what was there.

By integrating the cooling water system for the fuel cell 50 and the cooling water system for the hydrogen storage alloy tank 51, the exothermic reaction of the fuel cell and the endothermic reaction at the time of hydrogen release of the hydrogen storage alloy are balanced, The heat in the system can be effectively used.
Therefore, in general, a hydrogen storage alloy having a higher hydrogen desorption temperature has a larger hydrogen storage capacity, but by integrating the cooling water system of both, a high temperature type hydrogen storage alloy can be obtained without attaching a special heating source. Can be used,
The hydrogen tank 51 can be downsized (directly connected to weight reduction) or the hydrogen storage capacity can be increased. In addition, since the hydrogen storage alloy takes charge of the function of the radiator that has been conventionally required to cool the cooling water for the fuel cell 50, the radiator 84 may have a small capacity of itself.
It becomes possible to adopt a small radiator.

By integrating the cooling water system for the fuel cell 50 and the cooling water system for the hydrogen storage alloy tank 51, it becomes possible to combine the pumps individually required in the past with one pump. . Since the cooling water system L30 and the humidification water system L40 are independently configured, the cooling water to be added to the cooling water system L30 does not necessarily need to be pure water, and an antifreeze liquid can be used. This makes it easy to prevent freezing in cold regions or during cold weather. Moreover, it is not necessary to make the pipe of the cooling water system L30 and the radiator 84 from an expensive stainless material as in the conventional case, and an inexpensive material can be used for the pipe, and the radiator 84 cannot be made of a conductive material. It can be made of a material having excellent heat resistance, and this also allows the radiator to be downsized. Since the cooling water system L30 and the humidifying water system L40 are independently configured, the amount of water used for the humidifying water system L40 can be small, that is, the absolute amount of water required to remove dissolved ions is small, The deionization filter 91 may be a small one.

Further, according to this embodiment, the hydrogen gas system L1
0, the hydrogen circulation pump 55 is installed on the inlet port 50a side of the fuel cell 50, that is, on the downstream side of the confluence portion of the hydrogen recirculation pipe 60 in the hydrogen supply pipe 52. When the temperature is low, that is, when the hydrogen release pressure of the hydrogen storage alloy is low, the pressurized gas can be supplied to the fuel cell 50 by the discharge pressure of the pump 55. Further, since the hydrogen gas pressure in the fuel cell 50 is adjusted by the relief valve 61 having the atmospheric pressure as the reference pressure, even if the hydrogen release pressure of the hydrogen storage alloy is high (the hydrogen storage alloy is When the temperature reaches the predetermined temperature), the hydrogen gas pressure in the fuel cell 50 can be kept constant.

Further, according to this embodiment, the hydrogen gas system L1
Since the gas / liquid separator 58 of 0 and the water storage tank 77 of the humidifying water system L40 are connected via the water conduit 94, the pure water trapped by the separator 58 is appropriately disposed in the water conduit 94. The water tank 7 is opened by opening the solenoid valve 95.
Can be replenished to 7. For example, in the above embodiment,
The hydrogen gas system L10 is configured to always circulate hydrogen gas at a constant flow rate regardless of the output of the fuel cell 50. Therefore, when the fuel cell has a low output, the water trapped by the hydrogen gas system L10 is The amount (generally, the amount of humidifying water with respect to hydrogen gas) is larger than the amount of water generated by the reaction of the fuel cell 50 (the amount of water trapped in the air system L20), When the amount of water in the water storage tank 77 decreases, the water in the separator 58 can be easily replenished to the water storage tank 77 by opening the solenoid valve 95. Further, the water trapped by the hydrogen gas system L10 is sent to the exhaust side of the fuel cell 50, which is preferable in terms of safety. Explaining this point in detail, hydrogen is dissolved in the condensed water trapped by the hydrogen gas system L10, but since a large amount of air having a small oxygen ratio is discharged from the fuel cell 50 as exhaust gas. Even if hydrogen gas is released from the condensed water sent to the exhaust side of the fuel cell 50, this hydrogen gas will be diluted with the exhaust gas, so that no problem will occur. Further, the check valve 9 is attached to the water conduit 94.
Since 6 is provided, it is possible to prevent the exhaust gas from entering the hydrogen gas system L10.

[Brief description of drawings]

FIG. 1 is an overall system diagram of a fuel cell power generation system according to an embodiment of the present invention.

FIG. 2 is a diagram showing the flow of humidifying water in the fuel cell used in the system of the embodiment.

FIG. 3 is a diagram showing the flow of cooling water in the fuel cell used in the system of the embodiment.

FIG. 4 is a diagram showing a structure of a humidifying part in a fuel cell used in the system of the embodiment.

FIG. 5 is an overall system diagram of a conventional fuel cell power generation system.

FIG. 6 is a diagram showing a flow of cooling water in a fuel cell used in a conventional system.

FIG. 7 is a diagram showing a flow of hydrogen gas in a fuel cell used in a conventional system.

FIG. 8 is a diagram showing the flow of air in a fuel cell used in a conventional system.

[Explanation of symbols]

 50 Solid Electrolyte Fuel Cell 50g, 50h Port for Humidifying Water 51 Tank with Hydrogen Storage Alloy 52 Hydrogen Gas Supply Pipe 55 Pump 58 Gas / Liquid Separator 60 Hydrogen Gas Reflux Pipe 61 Relief Valve 66 Exhaust Pipe 73 Condenser 77 Water Storage Tank 93 Accumulation tank 93a Inert gas or air 94 Water conduit 96 Check valve 97 Fuel cell power generation zone 98 Fuel cell humidification zone B Fuel cell power generation system L10 Hydrogen gas system L20 Air system L30 Cooling water system L40 Humidification water system

Claims (9)

[Claims] 1. A cooling water system for cooling a fuel cell, comprising a hydrogen storage alloy as a hydrogen gas source and a solid polymer electrolyte fuel cell for generating power by receiving hydrogen gas as a fuel from the hydrogen storage alloy. And a humidifying water system for humidifying the gas supplied to the fuel cell, each independently connected to the fuel cell. 2. The fuel cell has a power generation section for generating power by a reaction and a humidification section for humidifying the supplied gas, and the cooling water supplied from the cooling water system is passed through the humidification section. An apparatus according to claim 1, consisting of: 3. The apparatus according to claim 1, wherein the cooling water system for the hydrogen storage alloy and the cooling water system for the fuel cell are constituted by a common cooling water system. 4. A water storage tank for storing water separated from gas discharged from the fuel cell, and a pressure storage tank enclosing the gas, wherein the water storage tank and the pressure storage tank are of the fuel cell. The device according to any one of claims 1 to 3, which is connected to two humidification water ports that communicate with the humidification unit, respectively. 5. The device according to claim 4, wherein the water storage tank is covered with an insulating material. 6. A fuel supply pipe for supplying hydrogen gas to the fuel cell, and a return pipe for returning hydrogen gas discharged from the fuel cell to the fuel supply pipe, wherein the fuel supply pipe includes: The apparatus according to any one of claims 1 to 5, wherein a pump is arranged on the downstream side of the confluence portion of the reflux pipe. 7. The apparatus according to claim 6, wherein the reflux pipe is provided with a relief valve that operates at an absolute pressure. 8. The fuel cell is further supplied with air as an oxidant,
A condenser, which is interposed in an exhaust air passage through which air discharged from the fuel cell passes, removes water from the air passing through the exhaust air passage, a water storage tank for storing water condensed by the condenser, and a gas It has an enclosed accumulator tank and a separator for separating water from the hydrogen gas discharged from the fuel cell, and the drain passage of the separator has a check valve to allow the exhaust air in the condenser to flow. The device according to claim 1, wherein the device is connected to a passage, and the water storage tank and the pressure storage tank are respectively connected to two humidification water ports that communicate with the humidification section of the fuel cell. 9. The fuel cell is further supplied with air as an oxidant,
A condenser for removing water from the air discharged from the fuel cell, a water storage tank for storing the water condensed by the condenser, a pressure accumulating tank for enclosing the gas, and water for discharging water from the hydrogen gas discharged from the fuel cell. A separator for separating, wherein the drainage passage of the separator is an exhaust air passage through which the air discharged from the fuel cell passes through a check valve, and the exhaust air on the upstream side of the condenser The device according to claim 1, wherein the device is connected to a passage, and the water storage tank and the pressure storage tank are respectively connected to two humidification water ports that communicate with the humidification section of the fuel cell.