JP2015133268A - Electric power generation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power generation apparatus including a metal-air battery and a hydrogen fuel cell, and suitable for securing a predetermined flow rate of hydrogen.SOLUTION: The metal-air battery generates power by a main reaction and generates hydrogen by a side reaction. The hydrogen fuel cell generates power by receiving hydrogen supplied from outside. A pressure conversion device increases pressure of hydrogen generated in the metal-air battery and provides the pressure-increased hydrogen to the hydrogen fuel cell.

Description

  The present invention relates to a power generation device including a metal-air battery and a hydrogen fuel cell.

  In the metal-air battery, as the discharge reaction, which is the main reaction, proceeds, the electrolytic solution is decomposed as a side reaction, and as a result, hydrogen is generated. For example, a technique for supplying hydrogen gas generated from a magnesium air battery to a fuel cell has been proposed (Patent Document 1). Thereby, hydrogen can be used effectively.

JP 2012-239245 A

  In order to perform efficient power generation with the hydrogen fuel cell, it is preferable to secure a predetermined hydrogen flow rate required by the hydrogen fuel cell. It is difficult to ensure a sufficient hydrogen flow rate required for a hydrogen fuel cell only by connecting the magnesium air cell and the hydrogen fuel cell with a gas transport line. An object of the present invention is to provide a power generator that includes a metal-air battery that generates hydrogen by a side reaction and a hydrogen fuel cell, and that is suitable for securing a required hydrogen flow rate.

According to one aspect of the invention,
A metal-air battery that generates electricity in the main reaction and generates hydrogen in the side reaction;
A hydrogen fuel cell that generates electricity by receiving hydrogen supply from the outside;
There is provided an electric power generation device including a pressure conversion device that raises a pressure of hydrogen generated in the metal-air battery and supplies the hydrogen fuel cell with the pressure.

  By increasing the pressure of the hydrogen generated in the metal-air battery and supplying it to the hydrogen fuel cell, it becomes possible to supply the hydrogen fuel cell with a required flow rate required by the hydrogen fuel cell.

FIG. 1 is a schematic diagram of a power generator according to an embodiment. FIG. 2A is a schematic diagram of a power generation device according to another embodiment, and FIG. 2B is a graph showing temporal changes in hydrogen gas pressure and flow rate. FIG. 3 is a schematic diagram of a power generating apparatus according to still another embodiment. FIG. 4 is a timing chart of opening / closing of the valve and heater on / off of the power generation apparatus according to the embodiment shown in FIG. 3, and a graph showing temporal changes in the flow rate and pressure of hydrogen gas. FIG. 5 is a schematic diagram of a power generation apparatus according to another embodiment.

In FIG. 1, the schematic of the electric power generator by an Example is shown. The power generator includes a metal-air battery 10, a hydrogen fuel battery 20, a hydrogen separator 18, and a pressure converter 3 that generate hydrogen by a side reaction.
0 and the flow rate adjusting mechanism 40.

  Hereinafter, the structure of the metal-air battery 10 will be described. A metal electrode 12 and an air electrode (oxygen electrode) 13 are arranged in the housing 11 with a space therebetween. The air electrode 13 is exposed to the outside through an opening provided in the housing 11. An electrolytic solution 14 is accommodated in the housing 11. For the metal electrode 12, for example, a laminate including a conductor layer and a negative electrode active material layer is used. For the negative electrode active material layer, for example, magnesium or a magnesium alloy is used.

  The air electrode 13 is a laminate including a conductor layer, an insulating porous layer, and a net-like support layer. The net-like support layer is disposed on the outermost side, and the conductor layer is disposed on the innermost side. The conductor layer is formed, for example, by applying a conductive material slurry to a current collector made of foamed nickel and then drying and firing. As an example, ketjen black is used as the conductive material of the conductive material slurry, and polytetrafluoroethylene is used as the binder. The insulating porous layer is permeable to oxygen and not permeable to moisture. The net-like support supports the insulating porous layer and the conductor layer. As the electrolytic solution 14, for example, a sodium chloride aqueous solution (brine) is used.

  The negative electrode terminal 15 is electrically connected to the metal electrode 12, and the positive electrode terminal 16 is electrically connected to the conductor layer of the air electrode 13.

In the metal electrode 12, the following main reaction occurs.
Mg → Mg ²⁺ + 2e ⁻
Furthermore, the following side reaction occurs.
Mg + 2H ₂ O → Mg (OH) ₂ + H ₂
The following reaction occurs at the air electrode 13.
O ₂ + 2H ₂ O + 4e ⁻ → 4 (OH) ⁻
Electrons generated by the main reaction of the metal electrode 12 flow through an external circuit connected to the negative electrode terminal 15 and the positive electrode terminal 16 and are consumed by the air electrode 13. Thereby, a current flows through the external circuit. As described above, the metal-air battery 10 generates power by the main reaction and generates hydrogen by the side reaction.

  Hydrogen generated by the side reaction of the metal electrode 12 and air taken into the housing 11 through the air electrode 13 are introduced into the hydrogen separator 18 through the gas transport line. The hydrogen separator 18 separates hydrogen from air. The separated hydrogen is introduced into the pressure conversion device 30. The pressure conversion device 30 includes, for example, a pressurizing pump 31, raises the pressure of hydrogen generated in the metal-air battery 10, and supplies it to the hydrogen fuel cell 20.

  A pressure gauge P and a flow rate adjusting mechanism 40 are attached to the gas transport line from the pressure conversion device 30 to the hydrogen fuel cell 20. The pressure gauge P measures the pressure of hydrogen raised by the pressure conversion device 30.

  The flow rate adjusting mechanism 40 includes a valve V <b> 1, a flow meter F, and a control device 41. As the valve V1, a valve capable of blocking the hydrogen gas flow and adjusting the flow rate is used. The control device 41 controls the valve V <b> 1 so that the flow rate measured by the flow meter F is within a certain range required by the hydrogen fuel cell 20. As described above, the flow rate adjustment mechanism 40 adjusts the flow rate of the hydrogen gas supplied from the pressure conversion device 30 to the hydrogen fuel cell 20 within a certain range required by the hydrogen fuel cell 20.

The hydrogen fuel cell 20 includes a fuel electrode 21, an air electrode 22, an electrolyte 23, a hydrogen channel 24, and an air channel (oxygen channel) 25. A negative electrode terminal 26 is electrically connected to the fuel electrode 21, and a positive electrode terminal 27 is electrically connected to the air electrode 22. Hydrogen gas transported from the pressure conversion device 30 flows through the hydrogen flow path 24 of the hydrogen fuel cell 20. The following reaction occurs at the fuel electrode 21.
H ₂ → 2H ⁺ + 2e ⁻
The following reaction occurs at the air electrode 22.
2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O

  Hydrogen flowing through the hydrogen flow path 24 is consumed at the fuel electrode 21, and hydrogen ions and electrons are generated. Hydrogen ions generated at the fuel electrode 21 are transported to the air electrode 22 through the electrolyte 23. Electrons generated at the fuel electrode 21 flow through an external circuit connected to the negative electrode terminal 26 and the positive electrode terminal 27 and reach the air electrode 22.

  The hydrogen ions transported in the electrolyte 23, oxygen flowing through the air flow path 25, and electrons reaching the air electrode 22 through an external circuit react to generate water (water vapor). The generated water vapor is discharged outside through the air flow path 25.

  In the embodiment shown in FIG. 1, the hydrogen gas generated in the metal-air battery 10 is raised while the hydrogen gas is being transported to the hydrogen fuel battery 20, so that the pressure of the hydrogen gas is increased from the metal-air battery 10 to the hydrogen fuel battery. 20, hydrogen can be efficiently transported. Further, since the flow rate of hydrogen is adjusted so as to be within the target range, power generation by the hydrogen fuel cell 20 can be stabilized.

  Another embodiment will be described with reference to FIGS. 2A and 2B. Hereinafter, differences from the embodiment shown in FIG. 1 will be described, and description of the same configuration will be omitted.

  FIG. 2A shows a schematic diagram of a power generator according to an embodiment. In this embodiment, the pressure conversion device 30 includes a pressurizing pump 31 and a buffer tank 32. The pressure gauge P measures the pressure in the buffer tank 32. Hydrogen delivered from the pressurizing pump 31 is supplied to the hydrogen fuel cell 20 via the buffer tank 32. The buffer tank 32 has a function of temporarily storing hydrogen. The control device 41 controls the valve V1 based on the measurement results of the pressure gauge P and the flow meter F.

  FIG. 2B shows an example of time waveforms of pressure and flow measured by the pressure gauge P and the flow meter F. At time t0, power generation by the metal-air battery 10 is started and hydrogen is generated. At this point, the valve V1 is closed. The generated hydrogen is stored in the buffer tank 32 via the pressure pump 31. For this reason, the pressure in the buffer tank 32 rises with time.

  At time t1, the pressure in the buffer tank 32 reaches the supply start threshold value PU. When the control device 41 detects that the pressure has reached the supply start threshold value PU, the control device 41 opens the valve V1. Further, the control device 41 controls the valve V1 so that the flow rate detected by the flow meter F becomes a constant value FH.

  When the amount (number of moles) of hydrogen supplied from the buffer tank 32 to the hydrogen fuel cell 20 per unit time is less than the amount (number of moles) of hydrogen generated from the metal-air battery 10, the pressure in the buffer tank 32 is Decreases over time. At time t2, the pressure decreases to the supply stop threshold PL. When the control device 41 detects that the pressure has become equal to or less than the supply stop threshold PL, the valve V1 is closed. Thereby, storage of hydrogen in the buffer tank 32 is resumed. As time elapses, the pressure in the buffer tank 32 increases, and at time t3, the pressure reaches the supply start threshold value PU. After time t3, the same processing as that after time t1 is repeated.

  As described above, in the embodiment shown in FIGS. 2A and 2B, the supply of hydrogen to the hydrogen fuel cell 20 is stopped when the pressure in the buffer tank 32 falls below the supply stop threshold PL. That is, during the period when hydrogen is supplied to the hydrogen fuel cell 20, the state in which the pressure in the buffer tank 32 is higher than the supply stop threshold PL is maintained. As a result, even when the generation rate of hydrogen from the metal-air battery 10 is not sufficient, it is possible to ensure the hydrogen flow rate required by the hydrogen fuel cell 20.

  Still another embodiment will be described with reference to FIGS. Hereinafter, differences from the embodiment shown in FIG. 1 will be described, and description of the same configuration will be omitted.

  In FIG. 3, the schematic of the electric power generator by an Example is shown. In this embodiment, the pressure conversion device 30 includes a hydrogen storage chamber 34 that houses the hydrogen storage alloy 35 and a heater 36. The heater 36 heats the hydrogen storage alloy 35. Hydrogen generated from the metal-air battery 10 is introduced into the hydrogen storage chamber 34 via the buffer tank 37 and the valve V5. Hydrogen introduced into the hydrogen storage chamber 34 is stored in the hydrogen storage alloy 35. Gases other than hydrogen, such as oxygen and nitrogen, are exhausted through valve V4.

  Valves V <b> 3, V <b> 2, and V <b> 1 are inserted in this order in the gas transport line from the hydrogen storage chamber 34 toward the hydrogen fuel cell 20. A pressure gauge P measures the pressure in the gas transport line between valves V3 and V2. The control device 41 controls the valves V1 to V5 and the heater 36 based on the pressure measured by the pressure gauge P and the flow rate measured by the flow meter F.

  When the heater 36 is off, hydrogen generated in the metal-air battery 10 is stored in the hydrogen storage alloy 35 in the hydrogen storage chamber 34. When the heater 36 is turned on, hydrogen stored in the hydrogen storage alloy 35 is released. By adjusting the release rate of hydrogen from the hydrogen storage alloy 35, the pressure of hydrogen delivered from the hydrogen storage chamber 34 can be increased. Thus, the hydrogen storage alloy 35 and the heater 36 function as a pressure conversion device 30 that increases the pressure of hydrogen generated in the metal-air battery 10.

  When the valve V5 is closed, the hydrogen generated in the metal-air battery 10 is temporarily stored in the buffer tank 37. By closing the valves V2, V4, V5 and opening the valve V3, the pressure in the hydrogen storage chamber 34 can be measured with the pressure gauge P. Hydrogen can be supplied from the hydrogen storage chamber 34 to the hydrogen fuel cell 20 by opening the valves V1, V2, and V3.

  FIG. 4 shows a timing chart of the opening degree of the valve V1, the opening / closing states of the valves V2 to V5, and the on / off state of the heater 36, the flow rate of hydrogen measured by the flow meter F, and the pressure time measured by the pressure gauge P. An example of the change is shown.

  At time t10, the valves V1 to V3 are closed and the valves V4 and V5 are opened. The heater 36 is off. In this state, hydrogen generated in the metal-air battery 10 is introduced into the hydrogen storage chamber 34 through the buffer tank 37 and the valve V5. Thereby, hydrogen is stored in the hydrogen storage alloy 35.

  At time t11, the valve V3 is opened, the valves V4 and V5 are closed, and the heater 36 is turned on. Hydrogen is released from the hydrogen storage alloy 35 and the pressure in the hydrogen storage chamber 34 increases. The pressure in the hydrogen storage chamber 34 is measured with a pressure gauge P.

At time t12, it is determined whether or not the pressure in the hydrogen storage chamber 34 is equal to or higher than the supply start threshold value PU. FIG. 4 shows a case where the pressure in the hydrogen storage chamber 34 is equal to or higher than the supply start threshold value PU at time t12. When the pressure in the hydrogen storage chamber 34 is equal to or higher than the supply start threshold PU, the supply of hydrogen from the hydrogen storage chamber 34 to the hydrogen fuel cell 20 is started by opening the valves V1 and V2. During the period when hydrogen is supplied to the hydrogen fuel cell 20, the opening degree of the valve V1 is adjusted so that the flow rate of hydrogen is constant. As hydrogen is released from the hydrogen storage alloy 35, the hydrogen release rate gradually decreases. For this reason, the pressure in the hydrogen storage chamber 34 gradually decreases. Hydrogen generated in the metal-air battery 10 is accumulated in the buffer tank 37.

  At time t13, the pressure in the hydrogen storage chamber 34 decreases to the supply stop threshold PL. When it is detected that the pressure in the hydrogen storage chamber 34 has decreased to the supply stop threshold PL, the valves V1 to V3 are closed, the valves V4 and V5 are opened, and the heater 36 is turned off. The supply of hydrogen to the hydrogen fuel cell 20 is stopped, and the pressure measured by the pressure gauge P is maintained at a value substantially equal to the supply stop threshold value PL. Hydrogen temporarily stored in the buffer tank 37 and hydrogen generated in the metal-air battery 10 are introduced into the hydrogen storage chamber 34, and storage of hydrogen in the hydrogen storage alloy 35 is started.

  At time t14, the valve V3 is opened, the valves V4 and V5 are closed, and the heater 36 is turned on. Release of hydrogen from the hydrogen storage alloy 35 is started, and the pressure measured by the pressure gauge P gradually increases. At time t15, it is determined whether the pressure in the hydrogen storage chamber 34 is equal to or higher than the supply start threshold value PU. FIG. 4 shows a case where the pressure in the hydrogen storage chamber 34 at time t14 is lower than the supply start threshold value PU.

  When the pressure in the hydrogen storage chamber 34 is lower than the supply start threshold PU, the valve V3 is closed, the valves V4 and V5 are opened, and the heater 36 is turned off. Thereby, the occlusion of hydrogen into the hydrogen occlusion alloy 35 is resumed.

  In the embodiment shown in FIGS. 3 and 4, when the hydrogen occlusion amount by the hydrogen occlusion alloy 35 is insufficient, hydrogen is not released from the hydrogen occlusion alloy 35 and the hydrogen occlusion is continued. When it is confirmed that the hydrogen storage amount by the hydrogen storage alloy 35 is sufficient, hydrogen is released from the hydrogen storage alloy 35 and hydrogen is supplied to the hydrogen fuel cell 20. For this reason, a sufficient flow rate of hydrogen can be stably supplied to the hydrogen fuel cell 20.

  FIG. 5 shows a schematic diagram of a power generator according to another embodiment. Hereinafter, differences from the power generation apparatus according to the embodiment shown in FIG. 1 will be described, and description of the same configuration will be omitted.

  Water (water vapor) generated in the hydrogen fuel cell 20 is transported to the metal air cell 10 via the water transport line 50. In the metal-air battery 10, water in the electrolytic solution 14 decreases due to side reactions. By transporting the water generated in the hydrogen fuel cell 20 to the metal-air battery 10, the electrolyte solution 14 can be supplemented with water.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

10 Metal-air battery 11 Housing 12 Metal electrode 13 Air electrode (oxygen electrode)
14 Electrolyte 15 Negative electrode terminal 16 Positive electrode terminal 18 Hydrogen separator 20 Hydrogen fuel cell 21 Fuel electrode (hydrogen electrode)
22 Air electrode (oxygen electrode)
23 Electrolyte 24 Hydrogen channel 25 Air channel (oxygen channel)
26 Negative electrode terminal 27 Positive electrode terminal 30 Pressure conversion device 31 Pressure pump 32 Buffer tank 34 Hydrogen storage chamber 35 Hydrogen storage alloy 36 Heater 37 Buffer tank 40 Flow rate adjusting mechanism 41 Control device 50 Water transport line V1 to V5 Valve F Flow meter FH Hydrogen Constant flow rate P Pressure gauge PU Supply start threshold PL Supply stop threshold

Claims (6)

A metal-air battery that generates electricity in the main reaction and generates hydrogen in the side reaction;
A hydrogen fuel cell that generates electricity by receiving hydrogen supply from the outside;
And a pressure converter for increasing a pressure of hydrogen generated in the metal-air battery to supply the hydrogen fuel cell.   The power generation apparatus according to claim 1, further comprising a flow rate adjusting mechanism that adjusts a flow rate of hydrogen supplied to the hydrogen fuel cell within a certain range required by the hydrogen fuel cell. further,
A valve inserted in a gas transport line from the pressure converter to the hydrogen fuel cell;
A control device for controlling the valve,
The pressure transducer has a function of storing hydrogen;
The control device closes the valve and stores the hydrogen in the pressure conversion device when the pressure of hydrogen increased in pressure by the pressure conversion device is lower than a predetermined supply stop threshold value, and the pressure conversion The hydrogen is supplied to the hydrogen fuel cell by opening the valve when detecting that the pressure of the hydrogen whose pressure has increased in the apparatus is equal to or higher than a predetermined supply start threshold value. Power generator.   The power generation device according to claim 3, wherein the pressure conversion device includes a buffer tank that temporarily stores hydrogen, and a function of storing hydrogen is realized by the buffer tank.   The pressure conversion device includes a hydrogen storage alloy and a heater that heats the hydrogen storage alloy, a function of storing hydrogen by the hydrogen storage alloy is realized, the hydrogen storage alloy is heated by the heater, The power generation device according to claim 3, wherein the function of increasing the pressure of hydrogen is realized by releasing hydrogen stored in the hydrogen storage alloy.   Furthermore, the electric power generator of any one of Claim 1 thru | or 5 which has a water transport line which transports the water which generate | occur | produced by the electric power generation by the said hydrogen fuel cell to the said metal air cell.

Images