JP2017135056A - Regeneration type fuel cell device and method for operating regeneration type fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regeneration type fuel battery device which can store hydrogen and oxygen with a simple structure without consuming an energy, and which never exhausts hydrogen, oxygen, and water to outside the device.SOLUTION: A regeneration type fuel cell device 100 comprises: a fuel battery 1 which uses hydrogen of a hydrogen-storing part 5 and oxygen of an oxygen-storing part 6 to generate an electric power; a water electrolyzing device 3 which electrolyzes resultant water to generate a hydrogen gas and an oxygen gas; a gas-liquid separator 4a, 4b with a pressure-resistant container, which introduces a hydrogen or oxygen gas resulting from electrolysis into the pressure-resistant container, and controls the flow rate of a hydrogen or oxygen gas flowing out of the pressure-resistant container so as to retain an internal pressure in the pressure-resistant container at a predetermined pressure or larger and to dehumidify the hydrogen or oxygen gas; the hydrogen-storing part 5 for serving to store the dehumidified hydrogen gas; and the oxygen-storing part 6 for serving to store the dehumidified oxygen gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a regenerative fuel cell apparatus, and more specifically, electrolyzes water using external electric power such as solar energy to store hydrogen and oxygen, and stores hydrogen and the like stored when electric power is needed. The present invention relates to a regenerative fuel cell device that supplies power to a battery to generate electric power.

  A fuel cell is a clean power generator that has high power generation efficiency and can be installed in a power consuming area, so there is no transmission loss, effective use of limited energy resources, and extremely low emission of air pollutants.

  The regenerative fuel cell that combines the fuel cell and the water electrolysis device generates hydrogen and oxygen by electrolyzing water and stores it when surplus power is obtained, and stores the hydrogen and oxygen stored when power is required. Can be electrochemically reacted to produce electricity and water.

The hydrogen and oxygen obtained by the water electrolysis contain moisture at a saturated vapor pressure, and when stored as it is, when supplying it to the fuel cell, the water covers the electrode surface, reducing the power generation efficiency of the cell, May deteriorate.
Therefore, in order to use hydrogen and oxygen obtained by the water electrolysis, it is necessary to remove the moisture to some extent.

Japanese Patent Application Laid-Open No. 2014-185387 of Patent Document 1 discloses dehumidification of hydrogen gas generated by water electrolysis with an adsorbent that can be heated and regenerated.
Japanese Patent Laid-Open No. 2013-231213 of Patent Document 2 discloses that hydrogen gas and oxygen gas generated by water electrolysis are further subjected to water electrolysis to reduce moisture in the hydrogen gas and oxygen gas. ing.
Furthermore, Japanese Patent Application Laid-Open No. 2013-227634 of Patent Document 3 expands and depressurizes oxygen generated by water electrolysis to lower the temperature, and heat-exchanges the reduced oxygen and hydrogen generated by water electrolysis. It is disclosed.

JP 2014-185387 A JP 2013-231213 A JP 2013-227634 A

  When the regenerative fuel cell is used not only on the ground but also in outer space, it is desirable to recycle all the water discharged from the fuel cell back to hydrogen and oxygen, and to store hydrogen and oxygen. It is preferable to reduce energy consumption associated with the operation of the regenerative fuel cell, such as energy.

  However, when the dehumidification method described in Patent Documents 1 to 3 is applied to a regenerative fuel cell, part of the removed water may be discharged outside the regenerative fuel cell, and the gas-liquid separation device However, it becomes complicated and large, and much energy is consumed for storing hydrogen gas and oxygen gas.

  The present invention has been made in view of such problems of the prior art. The object of the present invention is to prevent hydrogen, oxygen and water from being discharged outside the apparatus, and to store hydrogen and oxygen. An object of the present invention is to provide a regenerative fuel cell that can consume less energy with a simple structure.

  As a result of intensive studies to achieve the above object, the present inventor electrolyzed water discharged from the fuel cell with a water electrolysis device, and sequentially introduced the generated hydrogen and oxygen into the gas-liquid separation device. It has been found that the above object can be achieved by dehumidifying the internal pressure of the separation device at a predetermined pressure or higher, and the present invention has been completed.

That is, the regenerative fuel cell of the present invention includes a fuel cell, a water storage unit, a water electrolysis device, a gas-liquid separation device, a hydrogen storage unit, and an oxygen storage unit.
And the fuel cell generates power using hydrogen of the hydrogen storage part and oxygen of the oxygen storage part,
The water storage unit stores water discharged from the fuel cell;
The water electrolysis device is a water electrolysis device that generates hydrogen gas and oxygen gas by electrolyzing water in the water storage unit,
The gas-liquid separator has a pressure vessel, introduces hydrogen gas or oxygen gas generated by the electrolysis into the pressure vessel, and controls the flow rate of the hydrogen gas or oxygen gas flowing out from the pressure vessel. The dehydration of the hydrogen gas or oxygen gas is performed by maintaining the internal pressure of the container at a predetermined pressure or higher,
The hydrogen storage unit stores the dehumidified hydrogen gas, and the oxygen storage unit stores the dehumidified oxygen gas.

Also, a method for operating a regenerative fuel cell apparatus according to the present invention comprises a regenerative fuel comprising a fuel cell, a water storage unit, a water electrolysis device, a gas-liquid separator, a hydrogen storage unit, and an oxygen storage unit. This is a method of operating a battery device.
And the electric power generation process which generates electricity using the hydrogen of the hydrogen storage part and the oxygen of the oxygen storage part by the fuel cell,
A water storage process for storing water generated from the power generation process in a water storage unit;
A water electrolysis step of generating hydrogen gas and oxygen gas by electrolyzing water in the water storage unit with the water electrolysis device;
Hydrogen gas or oxygen gas generated in the water electrolysis process is introduced into the pressure vessel of the gas-liquid separator, and the flow rate of the hydrogen gas or oxygen gas flowing out from the pressure vessel is controlled to set the pressure inside the pressure vessel to a predetermined pressure. A gas-liquid separation step of dehumidifying the hydrogen gas or oxygen gas by maintaining the above,
A gas storage step of storing the dehumidified hydrogen gas in the hydrogen storage unit and storing the dehumidified oxygen gas in the oxygen storage unit.

  According to the present invention, the hydrogen and oxygen generated in the water electrolysis device and introduced into the gas-liquid separation device are increased in pressure by adjusting the flow rate when flowing out of the gas-liquid separation device. It is possible to provide a regenerative fuel cell capable of filling the hydrogen storage unit and the oxygen storage unit and dehumidifying without using a pump or the like and saving energy and increasing efficiency with a simple structure.

It is the schematic which shows an example of the regenerative fuel cell apparatus of this invention. It is the schematic which shows an example of a gas-liquid separator. It is a graph which shows a pressure change when controlling the flow volume of the gas taken out from a gas-liquid separator.

The regenerative fuel cell device of the present invention will be described in detail.
As shown in FIG. 1, the regenerative fuel cell device 100 includes a fuel cell 1, a water storage unit 2, a water electrolysis device 3, gas-liquid separators 4 a and 4 b, a hydrogen storage unit 5, and an oxygen storage unit 6. This is a closed-type regenerative fuel cell device that reuses hydrogen gas, oxygen gas, and water without discharging them to the outside.

The regenerative fuel cell apparatus 100 of the present invention uses a high-pressure water electrolysis apparatus as the water electrolysis apparatus 3.
The high-pressure water electrolysis apparatus is one that electrolyzes pure water by an electrolysis cell housed in a high-pressure vessel to generate hydrogen and oxygen, and the electrolysis cell is on both sides of a solid polymer electrolyte membrane (PEM). Have an electrode.

  The high-pressure water electrolysis apparatus electrolyzes pure water as it is and does not require the use of an additive such as an alkali. Therefore, corrosion of piping and the like is prevented, and stable operation is possible for a long time.

  Moreover, when water is electrolyzed, 22.4 L hydrogen gas and 11.2 L oxygen gas are obtained from 18 mL of water in a standard state, and the volume expands greatly. Therefore, by electrolyzing water in a sealed space, High-pressure hydrogen gas and oxygen gas can be generated without using a compressor.

  Then, the generated high-pressure steam-containing gas is successively introduced into the pressure-resistant container of the gas-liquid separator, and the pressure in the pressure-resistant container is increased to a predetermined pressure or more by adjusting the flow rate of the gas flowing out from the pressure-resistant container. If maintained, water vapor in the water vapor-containing gas is condensed and separated as water droplets, and the water vapor-containing gas becomes a gas with a lower dew point, so that water can be removed with high efficiency.

  Therefore, energy is not consumed for dehumidification of hydrogen gas and oxygen gas and filling of the storage unit, and a highly efficient regenerative fuel cell device can be obtained.

The gas-liquid separator will be described.
As shown in FIG. 2, the gas-liquid separation device includes a pressure vessel 41, an extraction conduit 42 for taking out hydrogen gas or oxygen gas, a drainage conduit 43, and a water level sensor 44 for detecting the water level in the pressure vessel 41. Prepare. The extraction conduit 42 has a back pressure valve 421, and the drainage conduit 43 has an electromagnetic valve 431.

  However, in the high-pressure water electrolysis apparatus, water is supplied to the hydrogen generation side, the oxygen generation side, or both to circulate, so the gas-liquid separation device on the water supply side does not have to provide the electromagnetic valve 431.

  The back pressure valve 421 of the extraction conduit 42 is set to open at a predetermined pressure, and the electromagnetic valve 431 of the drainage conduit 43 is opened when the water level in the pressure vessel 41 is higher than the predetermined water level. Is set.

  When wet gas containing hydrogen or oxygen and water vapor is successively introduced from the high-pressure water electrolysis apparatus into the pressure-resistant container of the gas-liquid separator, the pressure inside the pressure-resistant container 41 reaches the set pressure of the back pressure valve 421 of the extraction conduit 42. Pressure increases.

When the pressure of the wet gas (mixed gas) increases in the pressure vessel 41, the partial pressure of hydrogen gas or oxygen gas and the partial pressure of water vapor contained in the wet gas respectively increase.
However, when the partial pressure of water vapor reaches the saturated water vapor pressure at that temperature, the water vapor in excess of the saturated water vapor pressure is condensed into water, while hydrogen gas or oxygen gas is not condensed. The water vapor mole fraction is dehumidified.

  As described above, when a wet gas of hydrogen or oxygen is introduced from the high pressure water electrolysis apparatus into the pressure vessel 41 and the pressure in the pressure vessel 41 becomes higher than the set pressure of the back pressure valve 421 of the extraction conduit 42, a low dew point is obtained. Hydrogen gas or oxygen gas is discharged from the pressure vessel 41.

  Further, water (liquid) flows simultaneously with the hydrogen or oxygen wet gas from the high-pressure water electrolysis apparatus into the pressure vessel 41, and the water level in the pressure vessel 41 is raised together with the condensed water. When the water level in the pressure vessel 41 becomes higher than a predetermined water level, the electromagnetic valve 431 of the drainage conduit 43 is opened and water is discharged from the drainage conduit 43.

  However, in the gas-liquid separator on the side of supplying water to the high-pressure water electrolyzer, water is continuously discharged from the drainage conduit 43, so the electromagnetic valve 431 may not be provided.

  When the lower limit of the operating pressure (P) of the gas-liquid separator is Pmin, the upper limit is Pmax, the predetermined pressure for opening the back pressure valve 421 of the extraction conduit, that is, the pressure threshold corresponding to the necessary dew point condition is Pthr When the gas flow rate is not controlled by the back pressure valve 421, that is, when the gas pressure is normally open, the operating pressure (PNC) varies between Pmin and Pmax.

  On the other hand, the operating pressure (PC) when the gas flow rate is controlled by the back pressure valve 421 changes between Pthr and Pmax. That is, the back pressure valve is closed (opening degree 0) from Pmin to Pthr, and the back pressure valve 421 is gradually opened from the time when the pressure becomes Pthr or more.

  The operation pressure pattern of the gas-liquid separator is shown in FIG. In FIG. 3, the solid line represents the operating pressure (PC) when the gas flow rate is controlled by the back pressure valve of the extraction conduit. Moreover, a dotted line is an operating pressure (PNC) when the gas flow rate is not controlled, and shows a normal pressure increase accompanying filling with hydrogen gas or oxygen gas.

  When the gas flow rate is not controlled, the time average value of the water vapor pressure fraction Pv, s is expressed by the following equation.

  Further, the time average value of the pressure fraction of water vapor when the gas flow rate is controlled is expressed by the following equation when the time delay until reaching the predetermined pressure (Pthr) is ignored.

  Therefore, the amount of water vapor pressure fraction (water vapor mole fraction) reduced by controlling the gas flow rate is given by the following equation when the pressure increase rate (dP / dt) equal to or higher than the predetermined pressure (Pthr) is constant. expressed.

  Further, the converted water vapor pressure (Pv, a) obtained by converting the average value of the water vapor pressure fraction when the flow rate is controlled to atmospheric pressure is in an unsaturated state, and is expressed by the following equation.

When the dew point under atmospheric pressure at this time is represented by T _a (K), the following relationship is established according to Sontag's equation described in JIS Z-8806.

  Since the regenerative fuel cell apparatus of the present invention is a closed system for fluid and there is no fluid exchange with the outside, the dew point condition of hydrogen gas or oxygen gas is determined from the operational requirements of the regenerative fuel cell apparatus. The predetermined pressure (Pthr) may be set so that the water vapor pressure fraction and the dew point condition given by the above equation satisfy the operational requirements.

  The predetermined pressure (Pthr) may be automatically changed according to the state of the gas-liquid separator, or the gas-liquid separator can be cooled to a gas with a lower dew point.

  Although there is no restriction | limiting in particular as the said fuel cell 1, The fuel cell using the polymer electrolyte membrane (PEM) which shows high hydrogen ion conductivity in a wet state originally needs the water supply to an electrolyte membrane, Since it is not necessary to completely remove water vapor from the gas and oxygen gas, it can be preferably combined with the gas-liquid separator.

  Hereinafter, the present invention will be described in detail by embodiments, but the present invention is not limited to the following embodiments.

[Embodiment]
FIG. 1 shows a schematic configuration of a regenerative fuel cell apparatus according to Embodiment 1 of the present invention.
In FIG. 1, only hydrogen gas, oxygen gas, and water lines are shown, and electrical circuits such as loads are omitted. Moreover, the arrow of a line has shown the direction through which a fluid flows.

  A fuel cell 1 shown in FIG. 1 has a structure in which a plurality of fuel cell single cells each having a polymer membrane and electrodes on both sides of the polymer membrane are stacked, and includes a cooling device (not shown). An ion exchange membrane can be used as the polymer membrane, and a catalyst that promotes a cell reaction is disposed between the polymer membrane and each electrode.

Similarly to the fuel cell 1, the water electrolysis apparatus 3 has a structure in which a plurality of electrolytic single cells each having a polymer membrane and electrodes on both sides of the polymer membrane are stacked, and is housed in a high-pressure vessel.
In FIG. 1, the fuel cell 1 and the water electrolysis apparatus 3 are shown as separate units, but since power generation and water electrolysis are opposite reactions, an integrated fuel cell / water electrolysis that performs both power generation and water electrolysis is shown. It can also be a device.

  The hydrogen storage unit 5 is filled and stored with hydrogen gas, and the oxygen storage unit 6 is filled and stored with oxygen. The water storage unit 2 stores a predetermined amount of water (liquid).

  The fuel cell 1, the water storage unit 2, the water electrolysis device 3, the gas-liquid separation device 4, the hydrogen storage unit 5, the oxygen storage unit 6, and the conduit connecting them shown in FIG. It is not necessary to supply hydrogen gas, oxygen gas and water from the outside for the operation of the fuel cell device.

  In the water electrolysis process of electrolyzing water, the water in the water storage unit 2 is pumped by the pump 7a through the check valve 9c to the water circulation path between the water electrolyzer 3 and the gas-liquid separator 4 (gas-liquid separator 4 → pump 7b. → water electrolysis device 3 → gas-liquid separation device 4 → ...), and the water continuously discharged from the gas-liquid separation device 4b as the amount of water necessary for cooling the water electrolysis device 3 is also combined in the water circulation path. The high pressure water electrolyzer is supplied by the pump 7b.

Then, a positive voltage is applied to the oxygen side electrode of the high pressure water electrolysis apparatus, and a negative voltage is applied to the hydrogen side electrode.
Then, the water is oxygen-side electrode, oxygen gas (O ₂₎ and hydrogen ions (H ⁺⁾ Electronic (e ^-) is electrolyzed, hydrogen ions (H ⁺⁾ in the hydrogen side electrode through the polymer film It is transported and combined with electrons (e ⁻ ) that have reached the hydrogen side electrode through the electric circuit and become hydrogen gas (H ₂ ).

  Hydrogen gas and oxygen gas generated in the high-pressure water electrolyzer flows into the pressure vessel of the gas-liquid separator 4. In the gas-liquid separation step, the hydrogen gas or oxygen gas is dehumidified by controlling the flow rate of the hydrogen gas or oxygen gas to maintain the pressure in the pressure-resistant vessel at a predetermined pressure or higher.

  The water separated from the hydrogen gas by the gas-liquid separator 4a is discharged from the gas-liquid separator 4a when the water level in the gas-liquid separator 4a is higher than a predetermined water level, and the water circulation path is supplied by the pump 7b. To be supplied.

  On the other hand, the water separated from the oxygen gas by the gas-liquid separator 4b is continuously discharged from the gas-liquid separator 4b and supplied again (circulated water supply) to the high-pressure water electrolyzer by the pump 7b.

In the water circulation path, the water flowing on the anode side of the water electrolysis device 3 is circulated in a constant amount by the pump 7b.
At this time, the total amount of water (electrolytic consumption water) consumed in the gas generation reaction and water (membrane permeated water) permeating the cathode side of the water electrolysis device 3 and flowing into the gas-liquid separation device 4a is gas-liquid separation. It goes out of the device 4b.

However, when the gas-liquid separation device 4a reaches a certain level or more, the membrane permeated water collected by opening the electromagnetic valve 431 is returned to the circulation flow path, and water corresponding to the electrolytic consumption water is supplied from the water storage unit 2. Since it is sent and replenished by the pump 7a, the water level in the pressure vessel 41 is maintained substantially constant (above the lower limit) even when water is continuously discharged from the gas-liquid separator 4b, and oxygen gas flows through the water circulation path. There is no.
Then, when the water electrolysis process proceeds and there is no more water to be replenished from the water storage unit 2 to the water circulation path, the hydrogen storage unit 5 and the oxygen storage unit 6 reach the maximum filling amount, and the electrolysis of water is finished.

  The above is the operation when water is supplied to the oxygen side electrode of the high pressure water electrolysis apparatus. When water is supplied to the hydrogen side electrode, the hydrogen side is the operation of the gas-liquid separator 4b and the pump 7b, and the oxygen side is the gas-liquid separator 4a. Each operation of the pump 7a is performed.

  The dehumidified hydrogen gas or oxygen gas flows out from the gas-liquid separator 4 and flows into the hydrogen storage unit 5 and the oxygen storage unit 6 through the check valve 9a9b in the gas storage step, respectively, and is stored in a filled state.

Further, in the power generation process for generating power, when the pressure regulating valves 8a and 8b are opened, hydrogen gas (H ₂ ) is supplied to the hydrogen side electrode of the fuel cell 1 and oxygen gas (O ₂ ) is supplied to the oxygen side electrode. Is done.
Then, the hydrogen-side electrode with hydrogen gas under the action of the catalyst (H ₂₎ electrons (e ^-) is separated into hydrogen ions (H ^+), hydrogen ions (H ⁺⁾ to the oxygen side electrode through the polymer film At the oxygen side electrode, oxygen gas (O ₂ ), hydrogen ions (H ⁺ ), and electrons (e ⁻ ) that have passed through the electric circuit react to generate water, the oxygen side electrode is positive, the hydrogen side electrode A negative electromotive force is generated.

Hydrogen gas (H ₂ ) that has not reacted in the fuel cell 1 passes through the circulation conduit and is supplied again to the fuel cell 1.
The oxygen gas (O ₂ ) that has not reacted enters the water storage unit 2 together with the generated water to separate the water (water storage step), and the separated gas is supplied to the fuel cell again.

  As described above, a high-pressure hydrogen electrolyzer is used to obtain high-pressure hydrogen gas and oxygen gas, thereby filling the hydrogen storage unit 5 and oxygen storage unit 6 and dehumidifying the hydrogen gas and oxygen gas using a pressure pump. Can be done without.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Water storage part 3 Water electrolysis apparatus 4a Gas-liquid separation apparatus 4b Gas-liquid separation apparatus 41 Pressure-resistant container 42 Extraction conduit 421 Back pressure valve 43 Drainage conduit 431 Electromagnetic valve 44 Water level sensor 5 Hydrogen storage part 6 Oxygen storage part 7a Pump 7b Pump 8 Pressure regulating valve 9a Check valve 9b Check valve 9c Check valve 100 Regenerative fuel cell device

Claims (2)

A regenerative fuel cell device comprising a fuel cell, a water storage unit, a water electrolysis device, a gas-liquid separator, a hydrogen storage unit, and an oxygen storage unit,
The fuel cell generates power using hydrogen of the hydrogen storage unit and oxygen of the oxygen storage unit,
The water storage unit stores water discharged from the fuel cell;
The water electrolysis device is a water electrolysis device that generates hydrogen gas and oxygen gas by electrolyzing water in the water storage unit,
The gas-liquid separator has a pressure vessel, introduces hydrogen gas or oxygen gas generated by the electrolysis into the pressure vessel, and controls the flow rate of the hydrogen gas or oxygen gas flowing out from the pressure vessel. The dehydration of the hydrogen gas or oxygen gas is performed by maintaining the pressure in the container at a predetermined pressure or higher,
The regenerative fuel cell apparatus, wherein the hydrogen storage unit stores the dehumidified hydrogen gas, and the oxygen storage unit stores the dehumidified oxygen gas. An operation method of a regenerative fuel cell device comprising a fuel cell, a water storage unit, a water electrolysis device, a gas-liquid separator, a hydrogen storage unit, and an oxygen storage unit,
A power generation step of generating power using the hydrogen of the hydrogen storage unit and the oxygen of the oxygen storage unit by the fuel cell;
A water storage process for storing water generated from the power generation process in a water storage unit;
A water electrolysis step of generating hydrogen gas and oxygen gas by electrolyzing water in the water storage unit with the water electrolysis device;
Hydrogen gas or oxygen gas generated in the water electrolysis step is introduced into the pressure vessel of the gas-liquid separator, and the flow rate of the hydrogen gas or oxygen gas flowing out from the pressure vessel is controlled to set the pressure in the pressure vessel to a predetermined value. A gas-liquid separation step of dehumidifying the hydrogen gas or oxygen gas by maintaining the pressure or higher;
And a gas storage step of storing the dehumidified hydrogen gas in the hydrogen storage unit and storing the dehumidified oxygen gas in the oxygen storage unit.

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