JPH0529014A - Fule cell - Google Patents

Abstract

PURPOSE:To utilize waste heat so as to improve efficiency in a fuel cell by providing an exhaust oxidizer gas supply system by which at least part of exhaust oxidizer gas exhausted from an air electrode is made to flow into a heat exchange tube in a hydrogen storage alloy tank. CONSTITUTION:Heat generated according to power generation is removed through a cooling plate 4 by means of cooling water being circulated in a cooling water circulating system 17 by driving a pump 18, and is kept at an operation temperature of a fuel cell 1. The cooling water which became a high temperature due to removal of heat is cooled in a heat exchanger 19 by driving an air blower 21, and is flowed again into the plate 4. A part of high temperature exhaust air exhausted from an air electrode 3 flows into a heat exchanger tube in a hydrogen storage alloy tank 6 after passing through an exhaust air supply system 14, and is exhausted from an exhaust port 15. In this case, hydrogen storage alloy stored in the alloy tank 6 is heated by means of the high temperature exhaust air through the heat exchanger tube, and as a result of this, hydrogen is released from the hydrogen storage alloy, and is supplied to a hydrogen electrode 2. Furthermore, alloy, and is supplied to a hydrogen electrode 2. Furthermore, pressure of this released hydrogen is controlled so as to be put under prescribed pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell in which hydrogen stored in a hydrogen storage alloy is released by heating the alloy and used as a fuel.

[0002]

2. Description of the Related Art In general, a fuel cell has a basic unit of a unit cell in which an electrolyte holding layer is sandwiched and a hydrogen electrode and an air electrode are disposed on both sides of the layer, and the unit cells are stacked to form a plurality of unit cells. Each is equipped with a fuel cell body with a cooling plate interposed.
When hydrogen, which is a fuel, is supplied to the hydrogen electrode and an oxidant is supplied to the air electrode from the outside of the unit cell of the fuel cell main body, an electrochemical reaction occurs to generate electricity. The heat generated by this power generation is
Heat is removed by cooling water or cooling air as a cooling medium that flows through the cooling plate and is cooled by the cooling gas through the heat exchanger, and the operating temperature of the fuel cell is maintained. Here, oxygen in the air is generally used as the oxidant.

By the way, as a method of obtaining hydrogen as a fuel, there are a method of equipping a fuel cell with a hydrogen production apparatus and a method of transporting hydrogen produced by the hydrogen production apparatus in a storage tank and supplying it to the fuel cell. In this case, as a method of storing hydrogen in a storage tank, there is a method of filling a hydrogen cylinder at a high pressure and taking out hydrogen from the hydrogen cylinder, and the like. It is known to use it as fuel.

The characteristic of hydrogen storage by a hydrogen storage alloy is that hydrogen is present in the metal lattice that constitutes the alloy in an atomic state, so that hydrogen can be stored at a density higher than that of liquid hydrogen, and as a result, it is higher than atmospheric pressure. Even under slightly higher pressure conditions,
It is safe and can be stored in large quantities. This is a characteristic which is not present in the conventional cylinder storage method of storing in a gas state which is a general storage method. The types of hydrogen storage alloys include Mg-Ni alloys, Ti-Mn alloys, Ti-Zr.
Many alloys such as a Zr-Mn alloy and a Zr-Mn alloy are known. In any case, the hydrogen storage alloy generates heat when it absorbs hydrogen, and absorbs it when it releases it. This heat is 24000~65000J / mol -H _2. Therefore, in order to release hydrogen, it is necessary to supply this heat, but especially when releasing a large amount of hydrogen in a short time, it is necessary to secure the heat amount corresponding to the hydrogen release amount.

As a method for releasing hydrogen from the above hydrogen storage alloy to be used as a fuel for a fuel cell, reference is made to U.S. Pat. Gable
r Schiff & Hafen / Kommando
brücke, Heft 11/1988 Vol40
Have reported that the hydrogen storage alloy is heated by the heat of the cooling water that removes the heat generated during the power generation of the fuel cell to release hydrogen.

[0006]

In the above literature, cooling water for cooling the fuel cell main body is used as a method for releasing hydrogen from the hydrogen storage alloy. Paying attention to the fact that the high-temperature exhaust air that is discharged and the exhaust cooling gas that has become hot by cooling the cooling medium that flows through the cooling plate in the fuel cell body are usually discarded as waste gas. The heating of the hydrogen storage alloy with the discharged cooling gas to release hydrogen was investigated.

It is an object of the present invention to efficiently heat a hydrogen storage alloy with exhaust air discharged from an air electrode or a cooling gas for cooling a cooling medium for cooling a fuel cell body to release hydrogen and use it as a fuel. It is to provide a battery.

[0008]

In order to solve the above problems, according to the present invention, an electrolyte holding layer, a unit cell having a hydrogen electrode and an air electrode sandwiching the electrolyte holding layer, and heat generated during power generation are removed. A fuel cell main body having a cooling plate through which a heating cooling medium flows, a hydrogen storage alloy tank for storing a hydrogen storage alloy for generating hydrogen to be supplied to a hydrogen electrode, and a hydrogen storage alloy tank containing a heat transfer tube, and cooling the cooling medium. In a fuel cell including a heat exchanger that cools by heat exchange with gas, an exhausted oxidant gas supply system that causes at least a part of exhausted oxidant gas exhausted from an air electrode to flow through a heat transfer tube of a hydrogen storage alloy tank Shall be provided.

Further, in the above fuel cell, an exhaust cooling gas supply system is provided to allow at least a part of the exhaust cooling gas discharged from the heat exchanger to flow through the heat transfer tube in the hydrogen storage alloy tank.

In the above fuel cell, a pressure detector for detecting the pressure in the hydrogen storage alloy tank of hydrogen released by heating the exhausted oxidant gas passing through the exhausted oxidant gas supply system, and an external electrode from the air electrode A flow rate adjusting valve for controlling the flow rate of the discharged oxidant gas to be discharged and a control means for controlling the flow rate adjusting valve based on the deviation between the pressure detected by the pressure detector and the target value of the predetermined pressure are provided.

Further, in the above fuel cell, a flow rate detector for detecting a flow rate of hydrogen which supplies hydrogen released from the hydrogen storage alloy tank to the hydrogen electrode by heating the exhaust oxidant gas passing through the exhaust oxidant gas supply system, and an air A flow rate adjusting valve for controlling the flow rate of the discharged oxidant gas discharged from the electrode to the outside, and a control means for controlling the flow rate adjusting valve from the deviation between the flow rate detected by the flow rate detector and the target value of the predetermined flow rate are provided. And

In the above fuel cell, a pressure detector for detecting the pressure in the hydrogen storage alloy tank of hydrogen released by heating the exhaust cooling gas passing through the exhaust cooling gas supply system,
A flow rate adjusting valve for controlling the flow rate of the exhaust cooling gas discharged from the heat exchanger to the outside, and a control means for controlling the flow rate adjusting valve from the deviation between the pressure detected by the pressure detector and the target value of the predetermined pressure are provided. I shall.

Further, in the above fuel cell, heat exchange with a flow rate detector for detecting the flow rate of hydrogen supplied from the hydrogen storage alloy tank to the hydrogen electrode by releasing hydrogen released by heating the exhaust cooling gas passing through the exhaust cooling gas supply system. And a control means for controlling the flow rate adjusting valve based on the deviation between the flow rate detected by the flow rate detector and the target value of the predetermined flow rate. To do.

[0014]

[Function] A fuel cell body in which unit cells each having a hydrogen electrode and an air electrode sandwiching an electrolyte holding layer are laminated, and a cooling plate is inserted for each of the plurality of unit cells, is used as the supplied hydrogen and oxidant gas. The air causes an electrochemical reaction in a single cell to generate electricity. At this time, the heat generated at the time of power generation is removed by passing a cooling medium cooled by cooling gas in a heat exchanger through a cooling plate, and the operating temperature of the fuel cell is maintained.

At this time, at least a part of the high temperature exhaust air exhausted from the air electrode is passed through the exhaust oxidant gas supply system to the heat transfer tube in the hydrogen storage alloy tank, whereby the stored hydrogen storage alloy is removed. It is heated by exhaust air to release hydrogen and supply it to the hydrogen electrode as fuel.

Further, at least a part of the exhausted cooling gas, which has a high temperature due to heat exchange with the cooling medium flowing through the cooling plate and is discharged from the heat exchanger, is caused to flow through the heat transfer tube of the hydrogen storage alloy tank. Similar to the above, hydrogen is released from the hydrogen storage alloy and supplied to the hydrogen electrode as fuel.

Here, the amount of hydrogen supplied from the hydrogen storage alloy to the hydrogen electrode is controlled to a predetermined amount by controlling the pressure of the hydrogen released in the hydrogen storage alloy tank to a predetermined pressure. That is, the pressure in the hydrogen storage alloy tank of hydrogen released by heating the hydrogen storage alloy is detected by the pressure detector, and the amount of exhaust air discharged from the air electrode to the outside from the deviation between this detected pressure and the target value of the predetermined pressure. By controlling the flow rate control valve, the amount of exhausted oxidant gas flowing to the heat transfer tube in the hydrogen storage alloy tank via the exhausted oxidant gas supply system is controlled to heat the hydrogen storage alloy to release hydrogen stored in hydrogen. The pressure in the alloy tank is controlled to a predetermined pressure.

Further, the flow rate of hydrogen supplied from the hydrogen storage alloy tank to the hydrogen electrode is detected by a flow rate detector, and the amount of air discharged from the air electrode is determined from the deviation between the detected flow rate and a target value. By controlling the adjusting valve, the exhaust oxidant gas flowing from the air electrode through the exhaust oxidant gas supply system and through the heat transfer tube in the hydrogen storage alloy tank is controlled to heat the hydrogen storage alloy to discharge hydrogen from the hydrogen storage alloy tank. The amount of hydrogen supplied to the electrode is controlled to a predetermined amount.

When high-temperature cooling gas discharged from the heat exchanger and passing through the discharged cooling gas system is passed through the heat transfer tube of the hydrogen storage alloy tank to heat the hydrogen storage alloy and release hydrogen, The pressure of hydrogen released in the hydrogen storage alloy tank is detected by a pressure detector, and the amount of exhaust cooling gas discharged from the heat exchanger to the outside is detected from the deviation between the detected pressure and the target value of the predetermined pressure. By controlling the amount of exhaust cooling gas flowing through the exhaust cooling gas supply system to the heat transfer tubes in the hydrogen storage alloy tank to control the pressure in the hydrogen storage alloy tank of hydrogen released by heating the hydrogen storage alloy. Control to a predetermined pressure.

Further, the flow rate of hydrogen supplied from the hydrogen storage alloy tank to the hydrogen electrode is detected by the flow rate detector, and the flow rate of the exhaust cooling gas from the heat exchanger is determined from the deviation between the detected flow rate and the target value of the predetermined flow rate. By controlling the flow rate adjusting valve, the amount of cooling gas passing through the exhaust cooling gas supply system from the heat exchanger is controlled to control the amount of hydrogen supplied to the hydrogen electrode of the hydrogen that is heated and released from the hydrogen storage alloy.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a system diagram of a fuel cell according to Embodiment 1 of the present invention. In FIG. 1, a fuel cell body 1 of a fuel cell
Is provided with a hydrogen electrode 2, an air electrode 3 and a cooling plate 4 which are schematically shown. The hydrogen storage alloy tank 6 contains a heat transfer tube (not shown) and stores the hydrogen storage alloy.

The hydrogen supply system 7 is connected to the hydrogen storage alloy tank 6 and the hydrogen electrode 2, and supplies the hydrogen electrode 2 with hydrogen released by heating the hydrogen storage alloy. The hydrogen supply system 7 is provided with a pressure detector 8 for detecting the pressure of hydrogen released in the hydrogen storage alloy tank 6 according to the present invention. The hydrogen discharge system 9 is connected to the hydrogen electrode 2 and discharges hydrogen that does not contribute to the electrochemical reaction to the outside.

The air supply system 10 is provided with a blower 11 and is connected to the air electrode 3, and supplies air to the air electrode 3 by driving the blower 11. The air discharge system 12 is connected to the air electrode 3,
Air containing oxygen that does not contribute to the electrochemical reaction is discharged from the air electrode 3 to the outside. The air discharge system 12 has a flow rate adjusting valve 13 according to the present invention, and the air discharge system 12 upstream of the flow rate adjusting valve 13 is branched and connected to a heat transfer tube (not shown) of the hydrogen storage alloy tank 6 to connect the air electrode 3 to the air electrode 3. An exhaust air supply system 14 is provided to allow the exhaust air from the exhaust gas to flow through the heat transfer tube. 1
Reference numeral 5 is an outlet of the supply system 14.

The cooling water circulation system 17 comprises a pump 18 and a heat exchanger 19 via the cooling plate 4, and the pump 18
To circulate cooling water. The heat exchanger 19 cools the cooling water, which has become hot by cooling the fuel cell body 1 by the cooling plate 4, by exchanging heat with the cooling air.

The cooling air supply system 20 is provided with a blower 21 and is connected to the heat exchanger 19, and the cooling air is supplied to the heat exchanger 19 by driving the blower 21. The cooling air discharge system 22 discharges the cooling air, which has become high temperature due to heat exchange with the cooling water, from the heat exchanger 19 to the outside.

With such a configuration, the hydrogen storage alloy tank 6
The hydrogen which is released by heating described later and is supplied to the hydrogen electrode 2 of the fuel cell body 1 through the hydrogen supply system 7 and the air supplied to the air electrode 3 by the blower 11 make the fuel cell body 1 into a single cell. Generates an electrochemical reaction to generate electricity. At this time, exhausted hydrogen that does not contribute to the electrochemical reaction from the hydrogen electrode 2,
Exhaust air containing oxygen that does not contribute to the electrochemical reaction is exhausted from the air electrode through the hydrogen exhaust system 9 and the air exhaust system 12, respectively.

The heat generated by the power generation is removed by the cooling water circulated in the cooling water circulation system 17 by driving the pump 18 at the cooling plate 4, and is maintained at the operating temperature of the fuel cell.
The cooling water that has become high temperature by removing heat is used in the heat exchanger 19.
At, the air is cooled by the cooling air sent by the drive of the blower 21 and again flows into the cooling plate 4. On the other hand, the discharged cooling air which has become high temperature by cooling the cooling water is discharged through the cooling air discharging system 22.

By the way, at least part of the high-temperature exhaust air discharged from the air electrode 3 flows through the heat transfer pipe of the hydrogen storage alloy tank 6 via the exhaust air supply system 14, and is discharged from the discharge port 15. At this time, the hydrogen storage alloy stored in the hydrogen storage alloy tank 6 is heated by the high-temperature exhaust air via the heat transfer tube, and as a result, hydrogen is released from the hydrogen storage alloy and supplied to the hydrogen electrode 2.

Next, a control method for supplying a predetermined amount of hydrogen to the hydrogen electrode 2 will be described. The pressure of hydrogen released in the hydrogen storage alloy tank 6 is detected by the pressure detector 8, and a signal of this detected pressure is input to the pressure controller 25, and this controller supplies the detected pressure and a predetermined amount of hydrogen to the hydrogen electrode 2. The flow rate adjusting valve 13 provided in the air exhaust system 12 is controlled based on the deviation from the target value of the predetermined pressure sufficient for supply. With this control, the air exhaust system 12
By controlling the amount of exhaust air from the air electrode 3 exhausted from the hydrogen storage alloy tank 6 via the exhaust air supply system 14.
The hydrogen storage alloy is heated by controlling the amount of exhaust air flowing through the heat transfer tube, and the pressure of hydrogen released as a result is controlled to a predetermined pressure.

FIG. 2 is a system diagram of a fuel cell according to Embodiment 2 of the present invention. 1, a flow rate detector 27 for detecting the flow rate of hydrogen flowing through the hydrogen supply system 7 in place of the pressure detector 8 in FIG. 1 and a flow rate controller 28 in place of the pressure regulator 25 are provided in FIG. Is the same as.

In FIG. 2, when supplying a predetermined flow rate of hydrogen to the hydrogen electrode 2, the flow rate detector 27 detects the hydrogen flow rate,
The signal of the detected flow rate is input to the flow rate controller 28, and the flow rate control valve 13 provided in the air exhaust system 12 is controlled by the controller based on the deviation between the detected flow rate and the target value of the predetermined flow rate supplied to the hydrogen electrode. . By controlling the amount of exhaust air from the air electrode 3 exhausted from the air exhaust system 12 by this control, the amount of exhaust air flowing through the heat transfer tube of the hydrogen storage alloy tank 6 via the exhaust air supply system 14 is controlled to control hydrogen. The storage alloy is heated to release hydrogen at a predetermined flow rate and supply it to the hydrogen electrode 2.

FIG. 3 is a system diagram of a fuel cell according to Embodiment 3 of the present invention. In FIG. 3, the cooling air discharge system 22 is provided with a flow rate adjusting valve 30, which is branched from the cooling air discharge system 22 on the upstream side of the flow rate adjusting valve 30 and connected to the heat transfer pipe of the hydrogen storage alloy tank 6 to transfer the discharged cooling air. The same as FIG. 1 except that an exhaust cooling air supply system 31 for flowing the heat pipe is provided and the exhaust air supply system 14 is removed. In addition, 32 is an exhaust cooling air supply system 31.
It is the outlet of.

The hydrogen storage alloy stored in the hydrogen storage alloy tank 6 with such a configuration cools the cooling water from which the heat generated by the cooling plate 4 of the fuel cell body 1 in the heat exchanger 19 is removed. Therefore, the temperature rises, and the hydrogen is released by being heated by at least a part of the high-temperature exhaust cooling air flowing through the exhaust cooling air supply system 31 to the heat transfer tube of the hydrogen storage alloy tank 6. This hydrogen is supplied as a fuel to the hydrogen electrode 2 of the fuel cell body 1 via the hydrogen supply system 7.

When a predetermined amount of hydrogen is supplied to the hydrogen electrode 2, a signal of the detected pressure detected by the pressure detector 8 is input to the pressure regulator 25 as in the above, and the regulator detects the detected pressure and the predetermined pressure. The flow rate adjusting valve 30 is controlled based on the deviation from the target pressure value. By controlling the amount of exhaust cooling air from the heat exchanger 19 exhausted from the cooling air exhaust system 22 by this control, the amount of exhaust cooling air flowing through the heat transfer pipe of the hydrogen storage alloy tank 6 via the exhaust cooling air supply system 31. Is controlled to heat the hydrogen storage alloy, and the pressure of hydrogen released as a result is controlled to a predetermined pressure.

FIG. 4 is a system diagram of a fuel cell according to Embodiment 4 of the present invention. 4 is the same as FIG. 3 except that a flow rate detector 27 is provided instead of the pressure detector 8 of FIG. 3 and a flow rate adjuster 28 is provided instead of the pressure adjuster 25.

With such a configuration, when a predetermined flow rate of hydrogen is supplied to the hydrogen electrode 2 of the fuel cell main body 1, the flow rate of hydrogen flowing through the hydrogen supply system 7 from the hydrogen storage alloy tank 6 is detected by the flow rate detector 27. Is input to the flow rate controller 28, which controls the flow rate control valve 30 from the deviation between the detected flow rate and the target value of the predetermined flow rate. By controlling the amount of exhaust cooling air from the heat exchanger 19 exhausted from the cooling air exhaust system 22 by this control, the amount of exhaust cooling air flowing through the heat transfer pipe of the hydrogen storage alloy tank 6 via the exhaust cooling air supply system 31. Is controlled to heat the hydrogen storage alloy to release a predetermined amount of hydrogen and supply the hydrogen to the hydrogen electrode 2.

[0037]

As is apparent from the above description, according to the present invention, the high temperature exhaust air discharged from the air electrode of the fuel cell body or the cooling medium for cooling the fuel cell body is cooled in the hydrogen storage alloy tank. By guiding the high temperature exhaust cooling air that has been heated up, the hydrogen storage alloy in the hydrogen storage alloy tank can be heated to release hydrogen and be supplied to the hydrogen electrode of the fuel cell body. By providing the control means for controlling the pressure of released hydrogen or the flow rate of hydrogen supplied to the hydrogen electrode, the released hydrogen is supplied to the hydrogen electrode with its pressure or flow rate controlled to a predetermined value, and the fuel cell main body Since the electricity can be generated, the waste heat of the exhaust air or the exhaust cooling air can be used to heat the hydrogen storage alloy without providing a new heat source, and thus the efficiency of the fuel cell is improved.

[Brief description of drawings]

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

FIG. 2 is a system diagram of a fuel cell according to a second embodiment of the present invention.

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

FIG. 4 is a system diagram of a fuel cell according to Example 4 of the present invention.

[Explanation of symbols]

1 Fuel cell body 2 hydrogen electrode 3 air electrode 4 Cooling plate 6 Hydrogen storage alloy tank 8 Pressure detector 13 Flow rate adjustment valve 14 Exhaust air supply system 19 heat exchanger 25 Pressure regulator 27 Flow rate detector 28 Flow controller 30 Flow control valve 31 Exhaust cooling air supply system

Claims (6)

[Claims] 1. A fuel cell main body having an electrolyte holding layer, a unit cell having a hydrogen electrode and an air electrode sandwiching the electrolyte holding layer, and a cooling plate through which a cooling medium for removing heat generated during power generation flows. A fuel cell comprising a hydrogen storage alloy tank for storing a hydrogen storage alloy that releases hydrogen supplied to a hydrogen electrode and having a heat transfer tube built therein; and a heat exchanger for cooling the cooling medium by heat exchange with a cooling gas. A fuel cell comprising an exhaust oxidant gas supply system for allowing at least a part of the exhaust oxidant gas exhausted from the air electrode to flow through a heat transfer tube in the hydrogen storage alloy tank. 2. The fuel cell according to claim 1, wherein an exhaust cooling gas supply system is provided to allow at least a part of the exhaust cooling gas exhausted from the heat exchanger to flow through the heat transfer tube in the hydrogen storage alloy tank. Is a fuel cell. 3. The fuel cell according to claim 1, wherein a pressure detector for detecting the pressure in the hydrogen storage alloy tank of hydrogen released by heating the oxidant gas passing through the exhaust oxidant gas supply system, and an air electrode A flow rate adjusting valve for controlling the flow rate of the discharged oxidant gas discharged to the outside, and a control means for controlling the flow rate adjusting valve from the deviation of the pressure detected by the pressure detector from the target value of the predetermined pressure are provided. Characteristic fuel cell. 4. The fuel cell according to claim 1, wherein a flow rate detection for detecting a flow rate of hydrogen supplied from the hydrogen storage alloy tank to the hydrogen electrode, the hydrogen being released by heating the exhaust oxidant gas passing through the exhaust oxidant gas supply system. And a flow rate adjusting valve for controlling the flow rate of the discharged oxidant gas discharged from the air electrode to the outside, and a control means for controlling the flow rate adjusting valve based on the deviation between the detected flow rate of the flow rate detector and the target value of the predetermined flow rate. And shall be provided. 5. The fuel cell according to claim 2, wherein a pressure detector for detecting the pressure in the hydrogen storage alloy tank of hydrogen released by heating the exhaust cooling gas passing through the exhaust cooling gas supply system, and a heat exchanger. A flow control valve for controlling the flow rate of the discharged cooling gas discharged to the outside, and a control means for controlling the flow control valve from the deviation between the pressure detected by the pressure detector and the target value of the predetermined pressure are provided. Fuel cell to do. 6. The fuel cell according to claim 2, further comprising a flow rate detector for detecting a flow rate of hydrogen supplied from the hydrogen storage alloy tank to the hydrogen electrode, the hydrogen being released by heating the exhaust cooling gas passing through the exhaust cooling gas supply system. A flow rate adjusting valve for controlling the flow rate of the exhaust cooling gas discharged from the heat exchanger to the outside, and a control means for controlling the flow rate adjusting valve from the deviation between the flow rate detected by the flow rate detector and the target value of the predetermined flow rate. A fuel cell characterized by being provided.