Patent Application
20240011164
Embodiments of the present invention relate to a technology for separating gas and liquid from a multiphase fluid.
The gas-liquid separation device shown in Patent Literature 1 below is known as a gas-liquid separation device for separating gas and liquid from a multiphase fluid of gas and liquid. In the gas-liquid separation device shown in this document, swirl blades are disposed in a toroidal space defined by a casing and an exhaust pipe, and the upper part of the toroidal space is connected to an inlet, and the exhaust pipe is connected to the outlet at the upper part through its inner space. A swirl chamber is provided below the toroidal space, a liquid reservoir is provided below the swirl chamber, and a gap for liquid passage is provided between the outer edge of a partition member and the inner circumference wall of the casing. In this gas-liquid separation device, a multiphase fluid entering from the inlet is swirled by the swirl blades, and the liquid is separated and driven outward by the effect of centrifugal force, and flows down along the inner circumferential wall surface of the casing and through the gap into the liquid reservoir. On the other hand, the gas passes through the lower end of the exhaust pipe and flows out through the outlet.
Patent document 1: JP2002-028422
The gas-liquid separation devices described above have the problem of increasing the size of the apparatus because they require a toroidal space with swirl blades, a swirl chamber, a liquid reservoir, etc.
The problem solved by the present invention is to realize a technology that can provide apparatus in smaller sizes.
An aspect of the present invention that solves the above-mentioned problem is a gas-liquid separation device that separates liquid and gas from a gas-liquid multiphase fluid comprising a hydrophobic enclosure for the multiphase fluid formed by a hydrophobic membrane that allows only the gas in the multiphase fluid to pass through, and a supply channel that supplies the multiphase fluid to the hydrophobic enclosure.
Another aspect of the present invention is an electrolysis device that generates a gas by electrolyzing a liquid supplied to an electrolyte membrane between an anode-side electrode section and a cathode-side electrode section, comprising a liquid supply chamber in which the cathode-side electrode section is located and to which the liquid is supplied, a hydrophobic membrane that forms a part of the walls of the liquid supply chamber and that allows only a gas generated by the electrolysis on the cathode side of the electrolyte membrane to pass therethrough, and a discharge channel that discharges the gas that has passed through the hydrophobic membrane to the outside.
Embodiments of the present invention will be described below with reference to the drawings. Throughout the description and the drawings, elements having substantially the same functionality are given the same reference numbers to avoid redundant explanations.
The configuration of a gas-liquid separation device of the present embodiment will be described. In the following description, the multiphase fluid to be separated by the gas-liquid separation device of the embodiment is assumed to be a gas-liquid two-phase fluid in which a liquid such as water and a gas (in bubbles) such as air or water vapor are mixed in a multiphase manner.
As shown in
The liquid-side plate 20 has two inlet/outlet ports 41a and 41b, a liquid outlet port 21, and a gas outlet port 31 at the periphery of its flat front surface, as shown in
The gas-side plate 30 has two inlet/outlet ports 41a and 41b, a liquid outlet port 21, and a gas outlet port 31 at the periphery of its flat rear surface, as shown in
Each of the pair of inlet/outlet ports 41a and 41b communicates with a fluid flow channel 400 described below (see
Each of the pair of liquid outlet ports 21 communicates with a liquid flow channel 200, described below (see
A detailed description of the internal configuration of the flow channels and other components formed in the gas-liquid separation device 1 is given with reference to
As shown in
The inflow chamber 402 is in contact at its front side with one of the surfaces of a hydrophilic membrane 52 formed in a disk-shape, that is fixed by a separator or the like, not shown in the figure, between the liquid-side plate 20 and the gas-liquid mixture plate 40. Thus, the inflow chamber 402, together with the fluid flow channel 400, functions as a supply channel for supplying the multiphase fluid to the hydrophilic membrane 52.
The hydrophilic membrane 52 is a porous thin film made of a highly hydrophilic material that forms a wall of the inflow chamber 402, thereby forming a hydrophilic enclosure for the multiphase fluid. Therefore, in this embodiment, when wetted, the hydrophilic membrane 52 allows only the liquid in the multiphase fluid to permeate and pass through. Any known material may be used for the hydrophilic membrane 52 for passing only liquids as described above.
Within the liquid-side plate 20 on the front side of the hydrophilic membrane 52, a liquid flow channel 200 is formed to allow the liquid that has passed through the hydrophilic membrane 52, i.e., after the gas has been separated from the multiphase fluid, to flow in and to discharge the liquid to the outside. In other words, the hydrophilic membrane 52 forms one of the walls of the liquid flow channel 200.
The inflow chamber 403 is in contact at its rear side with one of the surfaces of a hydrophobic membrane 53 formed in a disk-shaped sheet, which is fixed by a separator or the like, not shown in the figure, between the gas-side plate 30 and the gas-liquid mixture plate 40. Thus, the inflow chamber 403, together with the fluid flow channel 400, functions as a supply channel for supplying the multiphase fluid to the hydrophobic membrane 53.
The hydrophobic membrane 53 is a porous thin film with gas permeability that forms one of the walls of the inflow chamber 403, thereby forming a hydrophobic enclosure for the multiphase fluid. This means that, in this embodiment, the hydrophobic membrane 53 allows only gases contained in the multiphase fluid to pass through without allowing liquids to pass through. Any known hydrophobic material may be used for the hydrophobic membrane 53 described above. An example is Gore-Tex (registered trademark) manufactured by WL Gore & Associates, Inc. from ePTFE (expanded polytetrafluoroethylene). The type of hydrophobic membrane 53 may be selected according to the environment in which it will be used, and may be either an organic or inorganic membrane. Examples of such inorganic membranes include ceramic membranes such as zeolite, silica, alumina, zirconia, and titania membranes, and carbon membranes. Examples of such organic membranes include fluoropolymer membranes such as PTFE (polytetrafluoroethylene) and PVDF (polyvinylidene fluoride) membranes, polyamide, cellulose acetate, polyimide, and polyethylene membranes. Alternatively, a porous material that has been made water-repellent may be used as a hydrophobic membrane.
Within the gas-side plate 30 on the rear side of the hydrophobic membrane 53, a gas flow channel 300 is formed to allow the gas that has passed through the hydrophobic membrane 53, i.e., after the liquid has been separated from the multiphase fluid, to flow in and discharge the gas to the outside.
The hydrophilic membrane 52 and the hydrophobic membrane 53 are made in the form of sheets and are arranged facing each other and separated from each other. Preferably, the separation distance should be less than a predetermined distance. The separation distance may be a distance based on the size of the bubbles in the multiphase fluid. By setting the separation distance smaller than the bubble size, the gas bubbles contained in the multiphase fluid can come into contact with both the hydrophilic membrane 52 and the hydrophobic membrane 53, allowing the gas to rapidly pass into the gas flow channel 300. Preferably, the distance should be about 1 mm to allow the multiphase fluid and the bubbles to contact the hydrophobic membrane 53. Therefore, the fluid flow channel 400 may be formed only by the hydrophilic membrane 52 and the hydrophobic membrane 53 by removing the aforementioned partitions 401a and 401b. That is, the front wall forming the fluid flow channel 400 is the hydrophilic membrane 52 and the rear wall is the hydrophobic membrane 53. On the other hand, when the multiphase fluid mainly consists of gas and is mixed, in a multiphase manner, with droplets such as water droplets, it is preferable to set the separation distance based on the droplet size in the multiphase fluid. By setting the separation distance smaller than the droplet size, the droplets contained in the multiphase fluid can come into contact with both the hydrophilic membrane 52 and the hydrophobic membrane 53, allowing the liquid to pass rapidly into the liquid flow channel 200.
The pore diameter and the number of pores per unit area of the hydrophilic membrane 52 and the hydrophobic membrane 53 should preferably be adjusted according to the type of gas and liquid to be separated and the supply pressure of the multiphase fluid.
The operation of the gas-liquid separation device 1 of this embodiment is described below. The following example shows a case where a multiphase fluid is supplied to each of the paired inlet/outlet ports 41a and 41b. When a multiphase fluid is first supplied to the paired inlet/outlet ports 41a and 41b, the multiphase fluid flows into the fluid flow channel 400 communicating with the inlet/outlet port 41a. The hatched arrow with the sign F1 in
When the multiphase fluid contacts the hydrophilic membrane 52, the liquid in the multiphase fluid passes through the hydrophilic membrane 52 and flows into the liquid flow channel 200. The hatched arrow with the sign L in
When the multiphase fluid contacts the hydrophobic membrane 53, the gas in the multiphase fluid passes through the hydrophobic membrane 53 and flows into the gas flow channel 300. The hatched arrow with the sign G in
In the embodiment described above, only the hydrophilic membrane 52 and the hydrophobic membrane 53 are used for gas-liquid separation to well achieve the gas-liquid separation function of separating liquids and gases in a multiphase fluid. As a result, the configuration of the device may be made extremely simple and the size of the device may be reduced compared to conventional devices. In particular, a sheet-shaped hydrophilic membrane 52 and a hydrophobic membrane 53 are arranged to sandwich the fluid flow channel 400, wherein the liquid flow channel 200 is formed adjacent to the hydrophilic membrane 52 and the gas flow channel 300 is formed adjacent to the hydrophobic membrane 53. As a result, the gas-liquid separation device 1 may be formed into a flat plate shape as shown in
In the description of this embodiment, the multiphase fluid to be separated in the gas-liquid separation was assumed to be a two-phase fluid of gas and liquid, but the multiphase fluid is not limited to such. Gas-liquid separation can even be performed for multiphase fluids having a higher phase, as long as the fluid is a liquid containing a gas.
The gas-liquid separation device of the first embodiment may be integrated into a water electrolyzer that produces hydrogen gas and oxygen gas by electrolyzing water. The second embodiment, which is a water electrolyzer with an integrated gas-liquid separation device, is described below.
The configuration of the water electrolyzer of this embodiment is described below.
The water electrolyzer 1A of this embodiment electrolyzes water into oxygen gas and hydrogen gas by means of a plurality of electrolytic cells 10A and the configuration and operation of each electrolytic cell 10A are equivalent. Therefore, the configuration and operation of one electrolytic cell 10A will be described hereafter.
First, the configuration of the electrolytic cell 10A is described in detail below. For the sake of explanation, a single electrolytic cell having end plates 60 and 70 on the front and rear sides will be described here as an example.
The end plates 60 and 70 are formed as square flat plates and form the front and rear walls of the electrolytic cell 10A. The electrolytic cell 10A is integrally formed into a generally rectangular shape by interposing the intermediate plate 61, the current collector plates 81a and 81b, and the intermediate plate 71 between the end plates 60 and 70, and fastening the end plates 60 and 70 with bolts and nuts. When the electrolytic cell 10A shown in
The intermediate plates 61 and 71 are shaped like the end plates 60 and 70, but are thicker. On the side of the intermediate plate 61 are a water supply pipe 611, a drain pipe 612 and two hydrogen discharge pipes 613. Inside the intermediate plate 61 are a water supply channel 614, a drain channel 615, and a hydrogen discharge channel 616 (see
Oxygen discharge pipes 711 are disposed at the bottom of the right surface and at the top of the left surface of the intermediate plate 71, as shown in
The internal configuration of the electrolytic cell 10A is described in detail below with reference to
As shown in
The MEA 80 is a generally rectangular plate-shaped member formed by sandwiching and bonding a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane), one side of which is a hydrogen side and the other side of which is an oxygen side, between gas diffusion electrode layers from the front and rear directions. It is preferable to use proton (H+) conducting porous electrolyte membranes, such as inorganic ceramics containing titanium hydroxide nanoparticles and proton-conducting Nafion (registered trademark).
The gas diffusion electrode layer is porous and permeable to hydrogen and oxygen gases. Materials such as porous carbon modified with Teflon (registered trademark), for example, can be used for such diffusion layers. A catalyst layer, such as platinum or gold, is provided between the gas diffusion electrode layer and the electrolyte membrane. In this embodiment, the catalyst layer is assumed to be formed on the electrolyte membrane. The electrolytic cell 10A in this embodiment is a cathode-feed type in which water is supplied only to the cathode side for electrolysis, and the water supplied to the cathode side passes through the electrolyte membrane and reaches the anode side. The gas diffusion electrode layer and the current collector plate 81a on the cathode side constitute the cathode-side electrode section, and the gas diffusion electrode layer and the current collector plate 81b on the anode side constitute the anode-side electrode section.
The MEA 80 is sandwiched or fixed between the current collector plates 81a and 81b via frame-shaped gaskets 82, which are located on both sides of the MEA 80 and connected to its peripheries. The current collector plates 81a and 81b are plate-shaped members for electrical connection to an external power supply for supplying voltage to the MEA 80, and in
A plurality of slits are also provided on the separator of the current collector plate 81b, and in the assembled state of the electrolytic cell 10A, an oxygen flow channel 713 (see
A square-shaped hydrophobic membrane 53 is arranged on the front side of the current collector plate 81a. The hydrophobic membrane 53 is arranged facing and separated from the MEA 80, and forms a part of the wall of the liquid supply chamber formed by the water channel 811. The functional description of the hydrophobic membrane 53 is omitted here, as it is equivalent to that described in the first embodiment. The hydrophobic membrane 53 is fixed to the current collector plate 81a and the separator across the frame-shaped gaskets 65 arranged on the periphery of both sides of the hydrophobic membrane 53. The carbon paper 64 having gas permeability for diffusing gas and water is interposed between the hydrophobic membrane 53 and the current collector plate 81a, and through the carbon paper 64, the hydrophobic membrane 53 can contact water and hydrogen gas which is in a bubbled state in the water.
It is preferable that the distance from the hydrophobic membrane 53 to the electrolyte membrane of the MEA 80, or more specifically to the catalyst layer on the cathode side, is made equivalent to the separation distance described in the first embodiment. This allows the hydrogen gas bubbles generated and adhering to the surface of the catalyst layer to contact the hydrophobic membrane 53 and thus immediately pass through the hydrophobic membrane 53. The separation distance, as in the first embodiment, is based on the bubble size of the gas produced, and should preferably be a distance at which the bubbles contact the hydrophobic membrane 53 before breaking away from the catalyst layer. For example, the separation distance may preferably be about 1 mm, where both water and bubbles can contact the hydrophobic membrane 53.
The separator 63, which is located on the front side of the hydrophobic membrane 53, is provided with a plurality of slits forming hydrogen flow channel 631 (see
Slits different from the slits forming the hydrogen flow channel 631 are formed on the separator 63, and the said slits function as water channels and connect the water flow channel formed by the water channel 811 of the separator on the current collector plate 81a to the water supply channel 614 formed on the intermediate plate 61. The separator 63 and the intermediate plate 61 are hermetically connected with the O-ring 62, which is an elastic member, interposed therebetween.
The operation of the electrolytic cell 10A of this embodiment is described below.
As shown in
Meanwhile, the water in the water channel 811 that has not been electrolyzed is discharged through the drain pipe 612 to the pump P1 through the drain channel 615 and is returned to the electrolytic cell 10A. The hydrogen gas generated by electrolysis at the interface between the anode-side gas diffusion electrode layer 802 and the electrolyte membrane 800 of the MEA 80 flows into the oxygen flow channel 713 and is discharged from the oxygen discharge pipe 711 through the oxygen discharge channel 712 to the outside of the electrolytic cell 10A and collected in a collecting container or the like.
In the water electrolyzer 1A of this embodiment described above, since the hydrophobic membrane 53 is disposed in the water channel 811, which is the cathode-side cathode chamber, the water circulates through the water channel 811, that is, between the hydrophobic membrane 53 and the MEA 80, to ensure gas-liquid separation along with electrolysis. In particular, hydrogen gas can be recovered in a good dry condition. Therefore, since the electrolytic cell is combined with a gas-liquid separation function, there is no need to prepare a separate gas-liquid separation device, and the device can be made much smaller than a water electrolyzer connected to a separate gas-liquid separation device. The device can be installed in a small space, such as a gap between other devices or structures, and can also be easily transported. Such a compact water electrolyzer 1A is extremely useful in environments such as space stations, where water electrolyzers are essential but installation space is limited, because it can operate even in a microgravity field.
When water is supplied to the cathode side on the ground, a gas phase portion exists in the water tank to absorb the pressure, but when water is electrolyzed in a microgravity field, an incompressible fluid such as water must be circulated in a closed container without a gas phase. When water is electrolyzed in an enclosed space, the gas generated in the electrolytic cell increases the pressure inside the electrolytic cell, causing a pressure imbalance between the oxygen side and the hydrogen side. If this condition is allowed to continue, the electrolyte membrane will be subjected to one-sided pressure, which may damage the membrane. In such cases, conventional devices would require a volume buffer device such as an accumulator.
However, in this embodiment, because the hydrogen gas generated by the MEA immediately passes through the hydrophobic membrane 53 and is vented, resulting in the volume buffering effect, a situation in which only one side is pressurized as a result of gas generation can be avoided. Therefore, since there is no need to use a volume buffer device, the cost can be reduced and the size can be made smaller. In addition, since only the cathode side needs to be supplied with water, only one pump P1 is required, and the cost can be reduced and the size can be made smaller.
There are some conventional methods in which water permeates from the periphery to the center of the electrolyte membrane of the MEA. In such methods, the effective membrane area of the electrode is smaller because the water path and the reaction path are independent. In addition, because the interface is maintained by surface tension, an imbalance between the pressure on the liquid side and the pressure on the gas side may cause liquid to leak into the gas side or gas to penetrate into the liquid. However, in this embodiment, because the water supplied to the MEA 80 is supplied to the entire surface of its electrolyte membrane 800, the only distance the water must penetrate is the thickness of the membrane. This allows for a smooth and flexible water supply path, and thus the water can be easily circulated.
The electrolytic cell 10A combined with a Sabatier reactor that produces methane (CH4) and water (H2O) from carbon dioxide (CO2) and oxygen (O2) can be made into an air regenerator. Air regeneration is the process of recovering O2 from CO2 exhaled by astronauts. Specifically, the CO2 emitted by organisms in an enclosed space is separated, concentrated, and fed into the Sabatier reactor. In the Sabatier reactor, the Sabatier reaction (CO2+4H2→CH4+2H2O) takes place, producing CH4 and H2O.
When the water produced by the Sabatier reaction in the Sabatier reactor is fed to the electrolytic cell 10A, hydrogen gas and oxygen gas are produced. The oxygen gas is used by organisms to breathe, and the hydrogen gas is returned to the Sabatier reactor. By repeating this cycle, oxygen can be regenerated from the carbon dioxide emitted by oxygen-breathing organisms, thus achieving air regeneration.
By stacking multiple electrolytic cells 10A as is done in the water electrolyzer 1A, the amount of hydrogen and oxygen gases produced can be increased compared to the case of only one electrolytic cell 10A. In this configuration, it is preferable that the water circulation supply paths (the water supply pipe 611 and the drain pipe 612) to and from the pump P1 are connected by a manifold so as to be shared by a plurality of electrolytic cells 10A. The same is true for the hydrogen and oxygen gas discharge paths (hydrogen discharge pipe 613 and oxygen discharge pipe 711).
The electrolytic cell 10B of
In particular, the electrolytic cell 10B can be constructed arranging, in a mirror-symmetrical manner with respect to the MEA 80, an intermediate plate 61, an O-ring 62, a separator 63, a carbon paper 64, a gasket 65, a hydrophobic membrane 53, another gasket 65, another carbon paper 64, and a current collector plate 81a in place of the current collector plate 81b, the O-ring 72, and the intermediate plate 71 of
By placing the hydrophobic membrane 53′ on the anode side, the same effect as on the cathode side can be obtained on the anode side, and good dry oxygen gas can be recovered. In addition, since water is supplied from both sides of the MEA 80, the heat generated in the cell by electrolysis can be dissipated more efficiently.
The amount of water required to produce oxygen for one person by electrolysis is small, about 0.5 grams per minute. On the other hand, conventional water electrolysis methods require pumps to circulate several liters of water to remove air bubbles from the electrodes and dissipate the heat generated there, a gas-liquid separation device, and electricity to run the equipment. However, in the electrolytic cell 10C of this variant embodiment, only a small amount of water (e.g., 0.5 grams per minute) is required for water electrolysis, and all of the supplied water can be electrolyzed. Therefore, compared with conventional systems, the pump P1 for circulating and supplying water and the gas-liquid separation device can be eliminated, and the oxygen gas generation system can be made much simpler, resulting in a more compact, lightweight and energy-saving system, as well as improved system reliability.
The electrolytic cell 10C can be integrated with the Sabatier reactor described in the first embodiment. In the conventional electrolytic cells, the temperature of the cells and of the Sabatier reactor was lost due to the circulation of the water. On the other hand, since the electrolytic cell 10C does not require water circulation, the reaction can be continued without lowering the temperature of the integrated Sabatier reactor. In addition, by stacking the electrolytic cell 10C and the Sabatier reactor, a very compact device can be obtained. The heat generated in the Sabatier reactor can also be used to heat the water electrolytic cell, reducing the voltage required for electrolysis.
In a system without water circulation, as in this variant embodiment, heat could build up in the cell. In such a case, the heat transfer pipes 12A, as shown in
The embodiments of the present invention have been presented by way of example only, and are not intended to limit the scope of the invention. The novel embodiments described herein may be embodied in a variety of other forms, and various omissions, substitutions and modifications may be made without departing from the spirit of the invention. The embodiments and modifications are included within the scope and/or spirit of the present invention as well as the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-033479 | Mar 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/008941 | 3/2/2022 | WO |
