WO2020162772A1

WO2020162772A1 - Electrolyzer for hydrogen and oxygen production

Info

Publication number: WO2020162772A1
Application number: PCT/PL2020/000013
Authority: WO
Inventors: Radosław DROŹDZIK
Original assignee: Felicitas A-C - Radosław Droździk
Priority date: 2019-02-08
Filing date: 2020-02-07
Publication date: 2020-08-13
Also published as: PL428847A1; PL238311B1; EP3921458A1

Abstract

This invention relates to an electrolyzer for hydrogen and oxygen production. The electrolyzer consists of a bottom cover (1) and an upper cover in form of two domes (5) and (14) equipped with a hydrogen sensor (8) and an oxygen sensor (17). Hydrogen port (6) is installed on the external surface of the dome (5). An oxygen port (15) is installed on the external surface of the dome (14). The domes (5) and (14) are permanently and tightly connected in their bottom middle part by a tank (1) partition (4). The partition (4) is permanently fixed to the opposite side walls above the tank (1) bottom and divides the tank (1) into the electrolytic cathode compartment (2) and the electrolytic anode compartment (3). A cathode pack (13) with a cord (7) is installed in the electrolytic cathode compartment (13). An anode pack (13) with a cord (16) is installed in the electrolytic anode compartment (3). The cathode pack (13) and the anode pack (22) consist of a metal core (24) with a permanently fixed upper support bar (25) and a bottom support bar (26) on which a supporting structure (27) of a cathode pack (13) plates (33) and an anode pack (22) plates (33) is mounted. Mounting strips (27) with horizontal guides (28) and vertical guides (29) are fixed to the supporting structure (27). The cathode pack (13) plates (33) and the anode pack (22) plates (33) are positioned vertically and parallel to one another at equal distances in the guides (28) and (29). A strip connecting (31) vertical guides (29) is installed in the cathode pack (13) and the anode pack (22) at the around ¾ of their height. The cathode pack (13) plate (33) and the anode pack (22) plate (33) consist of an enclosure made of a channel bar (36), inside of which there is a flat metal plate (34) whose flat side surfaces have permanently fixed coatings (35). The cathode pack (13) and the anode pack (22) consist of an electrode pack strip (33) that is wound around a metal core (24). The electrode pack strip (33) wound around the metal core (24) is positioned between a top supporting plate of a wound electrode pack (39) and a bottom supporting plate of a wound electrode pack (40) in a top spiral guide (41) and a bottom spiral guide (42).

Description

Electrolyzer for hydrogen and oxygen production

This invention relates to an electrolyzer for hydrogen and oxygen production.

Hydrogen (¾) , in particular adopted to power integrated systems (transport, construction eguipment and others) , is currently recognized as an energy carrier of the future instead of fossil fuels. Thus the hydrogen could ensure:

- solution to the problem of fossil fuel shortage;

- no C02 emission when used to power integrated systems resulting in reduction of the impact of human activity on climate changes;

- no emission of pollutants when used to power integrated systems by means of fuel cells, which significantly reduces the impact of exhaust gases on health especially in densely populated areas;

- significant reduction of noise resulting from its application to power integrated systems by means of fuel cells .

During electrolysis water undergoes decomposition at a cathode producing hydrogen bubbles and oxygen ions, which are transported by electrolyte creating oxygen molecules on an anode surface as a result of the detachment of electrons from them. To transport those electrons from anode to cathode to initiate the electrolysis it is necessary to provide electric energy. There are multiple known electrolyzer constructions and various types of generators intended for hydrogen and oxygen production, whose principle of operation is water electrolysis. Water electrolysis ensures clean technology for producing hydrogen which is then used e.g. as a fuel.

Production of hydrogen and oxygen by means of electric energy includes usage of electrolyzers or hydrogen and oxygen generators. They have various constructions. A common type of a construction includes PEM (Polymer Electrolyte Membrane) construction electrolyzers so they a use polymer membrane, which is permeable to protons. These types of electrolyzers are typically built as so-called stacks to achieve the highest possible gas output from a small volume, if possible. Water is supplied from one side to each membrane, on which, thanks to the electrodes placed on both sides of the membrane and electrolysis voltage provided, splitting of hydrogen and oxygen takes place. Hydrogen is accumulated on the one side of the membrane and oxygen on the other side of the membrane, to which water is fed.

A Polish patent application No. PL 225119, "Hydrogen and oxygen generator", discloses a generator for producing hydrogen and oxygen by water electrolysis. The generator consists of a hermetic reaction chamber filled with electrolyte. At least one pair of electrodes is inside the reaction chamber, where the first electrode is connected to the one pole and the second electrode to the second pole of a source of potential difference. The housing of the generator's reaction chamber is equipped with at least one discharge outlet pipe of electrolysis products, two discharge outlets of those products in a preferred solution, and at least one technological outlet pipe. The second electrode's assembly, which is mounted to the generator's base, has a form of at least two concentric walls with a closed cross section. The walls in the cross section along the generator's symmetry axis can have a shape of circle or other plane figure such as triangle, quadrangle or other polygon. The height of the mentioned walls, which are the generator's second electrode, is greater than the length of the pipes of the first electrode' s j ackets. However, the first electrode' s assembly has a form of at least two jackets installed tightly between a bottom insulation ring and an upper insulation ring to the upper plate of the reaction chamber. The jackets have a form of circular hollow sections or hollow sections with a cross section in form of a different plane figure. Symmetry axes of the jackets installed between bottom and upper insulation rings are arranged on a plan of concentric lines that are between the above mentioned concentric walls of the second electrode. Inside the mentioned jackets there is a first set of pipe electrodes. Inside the generator housing above the upper plate of the reaction chamber there is an accumulation chamber of the first product of electrolysis with the outlet pipe. Inside the generator housing there is also an accumulation chamber of the second product of electrolysis with its own outlet pipe that is separated from the accumulation chamber of the first product of electrolysis.

A Polish patent application No. PL 192845, "Method and device for producing hydrogen by electrolysis", discloses a method of producing hydrogen by electrolysis inside a tank containing liquid in a form of water, in which an electric signal in a form of impulses is transmitted between at least one pair of electrodes, which are at least partially submerged in water. The method is characterized in that the tank is filled up with liquid containing water until the tank is at least partially full then at least one pair of electrodes is submerged in the liquid, the electrodes are positioned in such a way that the distance between them is 5 mm or less, then after submerging and positioning the electrodes at a proper distance an electric impulse signal, whose signal length to pause ratio is between 1:1 and around 10:1, is transmitted to one of the electrodes and the electric impulse signal has frequency between around 10 kHz and around 250 kHz, and hydrogen is obtained.

A European patent application No. EP 2377972, "Device for electric generation of hydrogen", discloses a device for electric generation of hydrogen from water. This device is equipped with a PEM electrolyzer, one that operates using polymer electrolyte membrane that is permeable to protons. The electrolyzer is equipped with a water feeding inlet and a first outlet for hydrogen containing water and/or steam produced in the electrolyzer, as well as a second outlet for oxygen and water. Furthermore, the device is equipped with a water separation device whose outlet is connected by means of pipes with the first outlet of electrolyzer and whose outlet leads the gas to the hydrogen connector in or at the device where the water separation device includes a thermal separation stage. Inside the device there is an electrolyzer with the water separation device and the water separation device has the thermal separation stage. A mechanical separation device such as e.g. a cyclone separator or a gravitational separator, which is not a thermal separation stage, is a part of water separation device or a device installed before it as a primary separator. The water separation device consists of two or more stages where, in case of the first stage, it is a thermal separation stage in which water is separated from hydrogen stream by cooling.

A European patent application No. EP 2321448,

"Electrolytic combustible gas-producing apparatus", discloses a device that consists of a first tank with an inlet of continuous water flow and a second tank with a continuous outlet of water mixed with hydrogen and oxygen gas produced during electrolysis. Furthermore, the device is eguipped with one pipe connecting both tanks with its ends protruding slightly into the mentioned tanks and is connected to an electric terminal. The device is also eguipped with at least one core inside the pipe whose ends are placed in the tanks and which is connected to a second electric terminal with polarity opposite to the polarity of the first terminal where an external surface of the pipe mentioned is in contact with air directly or indirectly by means of fins to facilitate dissipation of heat generated during electrolysis.

A drawback of the solutions in the known state of the art devices and apparatuses producing hydrogen and oxygen by water electrolysis in conventional electrolyzers is the fact that those gases are usually generated in one cathode and anode compartment, which produce hydrogen and oxygen with limited efficiency in one electrode pack submerged in water. It means that it is necessary to supply a lot of electric energy to the electrodes to produce hydrogen and oxygen. System for separating products of water electrolysis in form of hydrogen and oxygen bubbles from the electrodes that is used in the known state of the art reguires that chemical catalysts and other compounds e.g. in form of sodium hydroxide or potassium hydroxide or other are added to process water. Furthermore, to separate gaseous product of electrolysis into hydrogen and oxygen complex, energy-consuming and low efficiency technologies are used. Hydrogen and oxygen produced in the electrolyzers known from the state of the art are of low purity and therefore require purification which is a very expensive process. Those inconveniences are solved by this invention.

According to the invention, an electrolyzer for producing hydrogen and oxygen consists of a bottom cover which is also a bottom and external walls of electrolyte tank as well as an upper cover in form of two domes equipped with hydrogen and oxygen sensors. The domes are permanently and tightly connected in their bottom middle part by the tank partition which is permanently fixed to the opposite side walls above the bottom of the electrolyte tank and divides the electrolyte tank into two compartments: the electrolytic cathode compartment and the electrolytic anode compartment. A cathode pack with a power cord is installed in the electrolytic cathode compartment and an anode pack with a power cord installed in the electrolytic anode compartment. The cathode pack and the anode pack consist of a metal core with a permanently fixed upper support bar and a bottom support bar on which a supporting structure and a cathode pack plate and an anode pack plate is mounted. Mounting strips with horizontal guides and vertical guides are fixed to the supporting structure. The cathode pack plate and the anode pack plate are positioned vertically and parallel to one another at equal distances in those guides. A strip connecting vertical guides is installed in the cathode pack and the anode pack at the around of their height. The cathode pack plate and the anode pack plate consist of an enclosure made of a channel bar, inside of which there is a flat metal plate whose flat side surfaces have permanently fixed coatings and a lug with a hole is fixed to the enclosure made of the channel bar. A system for feeding the cathode pack with electrolyte consisting of pipe elements, a water pump and a cathode directional cup with an injector, as well as a system for feeding the anode pack with electrolyte consisting of pipe elements, a water pump and an anode directional cup with an injector are installed in the electrolyzer.

A hermetic electrolytic tank is filled with water or other water-based liquid electrolyte. The partition is permanently and tightly mounted to the tank cover at the junction of the two domes and to the opposite side walls of the tank at the height that enables free flow of electrolyte between the electrolytic compartments. This partition does not adjoin the bottom of the electrolyzer tank enabling the liquid in—the—elect rolytic compartments to flow freely resulting in the process of continuous mixing of electrolyte in both compartments of electrolytic tank.

Construction of the cathode pack and the anode pack is identical .

Each cathode pack plate and anode pack plate is installed in the supporting structure of electrode pack in a special guide, which is favorably made of metal channel bars. The channel bars are screwed to the mounting strip installed in the upper part of the electrode structure on its opposite sides. The guides in which electrode pack plates are installed are mounted both to the bottom side of the supporting structure of electrode pack as well as to its vertical walls.

Plates of the electrode pack are positioned in the guides parallel to one another at equal distance enabling free flow of water or other liquid electrolyte between the electrode pack plates.

Favorably, each plate of the electrode pack consists of a flat metal plate whose two side surfaces have permanently fixed coating made of porous carbon material. Coatings made of porous carbon material are favorably fixed using electroconductive adhesive. Favorably, the porous carbon material is graphene.

There are holes in the mounting strip of the electrode pack construction as well as the mounting lug of the electrode pack plate facilitating connection of those elements with the screws . Favorably, instead of electrode pack plates the cathode pack and the anode pack consist of one longitudinal strip of electrode pack that is wound around a metal core so that a fixed distance enabling free flow of electrolyte is kept between them. The longitudinal strip of the electrode pack wound around the metal core is—positioned between a top supporting plate of a wound electrode pack and a bottom supporting plate of a wound electrode pack in a top and a bottom spiral guide.

A system forcing electrolyte circulation installed in the electrolytic compartments feeds directly the cathode pack and the anode pack. The system forcing supply of electrolyte to the electrolytic cathode compartment consists of pipe elements that suck in the electrolyte from the upper part of the electrolytic anode compartment. The system forcing supply of electrolyte to the electrolytic anode compartment consists of the pipe elements that suck in electrolyte from the upper part of electrolytic cathode.

Hydrogen bubbles produced as a result of electrolysis gather on the external surfaces of plates installed in the cathode pack and oxygen bubbles gather on the external surfaces of plates installed in the anode pack are accumulated on the dome that covers electrolytic cathode compartment and the dome that covers electrolytic anode compartment as a result of intensive electrolyte flow. Through the port installed in the dome covering the electrolytic cathode compartment the hydrogen is evacuated from the electrolyzer. Through a port installed in the dome covering the electrolytic anode compartment the oxygen is evacuated from the electrolyzer. A hydrogen pressure sensor is installed on the dome covering the electrolytic cathode compartment. An oxygen pressure sensor is installed on the dome covering the electrolytic anode compartment. A connector of liquid water- based electrolyte is installed on the outer front wall of the bottom part of the hermetic electrolytic tank.

According to the invention, there are two or more cathode packs and two or more anode packs installed in the electrolytic cathode compartment and electrolytic anode compartment to increase the electrolyzer capacity.—Two or more cathode packs and two or more anode packs are electrically connected in parallel to each other. Each of the multiple cathode packs and multiple anode packs are supplied by an electronic control and protection system.

Favorably, the plates or the strip of the cathode pack and the plates or the strip of the anode pack are made of graphene .

Reactions taking place in the electrolyzer are as follows:

Cathode: 4H⁺ + 4^e~ 2H₂

Anode: 2H₂0 - 4^e~ 0₂ + 4H⁺

Total reaction: 2H₂0 _® 0₂ + 4H₂

The above configuration of the system makes it possible to obtain gaseous hydrogen of high purity up to 99.99% H₂.

According to the invention, the hydrogen in the electrolyzer is favorably produced by electrolysis from purified tap water. First, water undergoes purification process using mechanical and osmosis filters.

The advantage of the electrolyzer according to the invention is its simple construction, possibility to use water supplied directly from the water grid in the electrolysis process, high efficiency per unit compared to the electrolyzers used so far, low unit cost of hydrogen production and very high purity of hydrogen, around 99.99% H₂, produced in the electrolysis according to the invention.

One of the embodiments of the electrolyzer for hydrogen and oxygen production according to the invention is disclosed in the drawing, in which Fig. 1 shows an example construction diagram of the electrolyzer, Fig. 2 shows an example construction diagram of a top view and a side view of the electrode pack as well as a front view of the electrode pack plate, Fig. 3 schematically shows a top view and a front view of the electrode pack, Fig. 4 shows a top view of the wound e1ectrode pack strip, and Fig _5 shows a_side—view of—a crocs section of the wound electrode pack strip.

The electrolyzer consists of a bottom cover 1 which is also a bottom and the external walls of electrolyte tank 1 as well as an upper cover in form of two domes 5 and 14 equipped with a hydrogen sensor 8 and an oxygen sensor 17. A hydrogen port 6 is installed on the external surface of the dome 5. An oxygen port 15 is installed on the external surface of the dome 14. The domes 5 and 14 are permanently and tightly connected in their bottom middle part by the tank 1 partition 4. The partition 4 is permanently fixed to the opposite side walls above the tank 1 bottom and divides the tank 1 into the electrolytic cathode compartment2 and the electrolytic anode compartment 3. A cathode pack 13 with a cord 7 is installed in the electrolytic cathode compartment 13. An anode pack with a cord 16 is installed in the electrolytic anode compartment. The cathode pack 13 and the anode pack 22 consist of a metal core 24 with a permanently fixed upper support bar 25 and a bottom support bar 26 on which a supporting structure 27 and of cathode pack 13 plates 33 and anode pack 22 plates is mounted. Mounting strips 27 with horizontal guides 28 and vertical guides 29 are fixed to the supporting structure 27. The cathode pack 13 plates 33 and the anode pack 22 plates 33 are positioned vertically and parallel to one another at equal distances in guides 28 and 29. A strip 31 connecting vertical guides 29 is installed in the cathode pack 13 and the anode pack 22 at the around ¾ of their height. The cathode pack 13 plate 33 and the anode pack 22 plate 33 consist of an enclosure made of a channel bar 36, inside of which there is a flat metal plate 34 whose flat side surfaces have permanently- fixed coatings 35. A lug 37 with a hole 38 is fixed to the enclosure made of the channel bar 36. A system for feeding the cathode pack 13 with electrolyte consisting of pipe elements

9 , a water pump 10 and a cathode_directional—cup.12—with an injector 11 is installed in the electrolyzer. A system for feeding the anode pack 22 with electrolyte consisting of pipe elements 9, a water pump 10 and an anode directional cup 12 with an injector 11 is installed in the electrolyzer. A water connector 23 is installed on the external front wall of the tank 1 at its bottom part. In other solution, the cathode pack 13 and the anode pack 22 consist of an electrode pack strip 33 that is wound around a metal core 24. The electrode pack strip 33 wound around the metal core 24 is positioned between a top supporting plate of a wound electrode pack 39 and a bottom supporting plate of a wound electrode pack 40 in a top spiral guide 41 and a bottom spiral guide 42.

Claims

1. An electrolyzer for hydrogen and oxygen production consisting of a housing with an electrolyte tank, a cathode pack and an anode pack, characterized in that it consists of a bottom cover (1) which is also a bottom and the external walls of electrolyte tank (1) as well as an upper cover in form of two domes (5) and (14) equipped with a hydrogen sensor (8) and an oxygen sensor (17) where the domes (5) and (14) are permanently and tightly connected at their bottom middle part by a tank (1) partition (4), and the partition (4) is permanently fixed to the opposite side walls above the tank (1) bottom and divides the tank (1) into two compartments: the electrolytic cathode compartment (2) and the electrolytic anode compartment (3), where a cathode pack (13) with a power cord (7) is installed in the electrolytic cathode compartment (2) and an anode pack (22) with a power cord (16) is installed in the electrolytic anode compartment (3) and the cathode pack (13) and the anode pack (22) consist of a metal core (24) with a permanently fixed upper support bar (25) and a bottom support bar (26) on which a supporting structure (27) of cathode pack (13) plates (33) and anode pack (22) plates (33) is mounted and the mounting strips (27) with horizontal guides (28) and vertical guides (29) are fixed to the supporting structure (27), where the cathode pack (13) plates (33) and the anode pack (22) plates (33) are positioned vertically and parallel to one another at equal distances in the guides (28) and (29) whereas the cathode pack (13) plate (33) and the anode pack (22) plate (33) consist of an enclosure made of a channel bar (36) , inside of which there is a flat metal plate (34) whose flat side surfaces have permanently fixed coatings (35) and a lug (37) with a hole (38) is fixed to the enclosure made of the channel bar (36) , in addition, a system for feeding the cathode pack (13) with electrolyte consisting of pipe elements (9), a water pump (10) and a cathode directional cup (12) with an injector (11) as well as a system for feeding the anode pack (22) with electrolyte consisting of pipe elements (9), a water pump (10) and an anode directional cup (12) with an injector (11) are installed in the electrolyzer.

2. The electrolyzer according to claim 1, characterized in that the cathode pack (13) and the anode pack (22) consist of a strip (33) with coatings (35) permanently fixed on both sides, which is wound around a metal core (34) between a top supporting plate of a wound electrode pack (39) in a spiral guide (42) and a bottom supporting plate of a wound electrode pack (40) in a spiral guide (41).

3. The electrolyzer according to claim 1, characterized in that the system for feeding cathode pack (13) with the electrolyte sucks in the electrolyte from the upper part of anode compartment (3) and the system for feeding anode pack (22) with the electrolyte sucks in the electrolyte from the upper part of cathode compartment (2) .

4. The electrolyzer according to claim 1 and 3, characterized in that the electrolyte is pure water or water based electrolytic fluid.

5. The electrolyzer according to claim 1 and 2, characterized in that that the coatings (35) permanently fixed to the side surfaces of flat metal plate (34) or to the side surface of wound strip (33) are made of porous carbon material .

6. The electrolyzer according to claim 5, characterized in

that the porous carbon material is graphene.