FI90568C - Electrolyser for hydrogen production - Google Patents

Description

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Electrolysis equipment for hydrogen production Elektrolysapparat for framstållning av våte 5

The invention relates to an electrolysis apparatus for producing hydrogen by decomposing an electrolytic liquid by means of an electric current in a sealed electrolytic cell placed in a pressurized pressure shell to hydrogen and oxygen.

10 Hydrogen is an ideal and pollution-free energy source for special applications where no normal energy sources are available. Thus, solar panels can be used to generate electricity in pre-inert areas in sparsely populated and difficult-to-navigate areas. Such facilities are often unmanned-15 and require automatic or remote operation. The equipment must also function when sunlight is not available. Storing electricity in batteries alone would require a very large number of batteries that are heavy and need maintenance.

20 The use of hydrogen as an energy store is one way of recovering the surplus energy produced by solar cells, in which case electricity is used to decompose water into hydrogen and oxygen. If necessary, electricity can then be produced from hydrogen using a fuel cell. However, in order to reduce the size of the required hydrogen stores, hydrogen must be pressurized and additional energy must be used during pressurization.

It is known to carry out the decomposition of water into hydrogen and oxygen in electrolytic cells which operate under pressure and thus produce hydrogen directly under pressure and no separate pressurization is required. However, the disadvantage of pressurizing the electro-30 lysis cell is the increase in leakage.

It is also known to place the electrolytic cell sisåån separate pressure shell, whereby the differential pressure of the electrolytic cell sisåpuolen and the outside 35 of the electoral law is substantially reduced and the leakage våhenevåt. Thus, for example, in the apparatus according to FR-2466515, the pressure shell is pressurized by means of nitrogen gas and the apparatus includes means for keeping the pressure inside the electrolytic cell lower than the pressure in the pressure shell.

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However, the use of a separate pressurizing gas requires the storage of pressurized gases and the need for replenishing the pressurized gas, and the system described in FR patent 2466515 is therefore not suitable, for example, for automatically operating solar power plants in remote areas.

It is known from 5 GB patent 1518234 to place electrolytic plates inside a pressure shell, whereby a pressure of hydrogen gas prevails inside the pressure shell. However, the structure according to the patent does not have a closed electrolysis cell placed inside the pressure shell, but the electrodes used for the decomposition of the electrolyte (HCl) are arranged to hang directly inside the pressure shell. The apparatus disclosed in GB patent 1518234 is a plant for large-scale hydrogen production with a very high power requirement, a complex structure and a calyx due to nun. cleaning equipment.

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The present invention relates to a pressurized electrolysis plant for the production of hydrogen which has solved the disadvantages of the systems described above and which can be advantageously applied to automatic solar energy applications without supervision and continuous maintenance.

The electrolysis apparatus according to the invention is characterized in that the electrolytic cell placed in the pressure shell is kept pressurized by the pressure of the oxygen generated in the electrolysis.

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The electrolytic liquid to be injected into the electrolytic cell contains water, but it may also contain any excipients which promote the operation of the electrolytic cell used, such as acids or bases. In the following, the term "water" means any such electrolytic fluid. 30

In the apparatus according to the invention, the normal advantages provided by pressurization are achieved, i.e. the generation of leaks from the electrolysis cell can be minimized. In addition, the invention provides many additional advantages.

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By means of the invention, it is possible to provide variable-pressure pressurization without the need to use a separate shielding gas or stored hydrogen for the pressurization and its adjustment. In particular, it should be noted that the pressurizing gas used in the apparatus according to the invention can be used except for variable pressure pressurization as a backup source of mycSs, since hydrogen gas and oxygen gas can be converted back to electric energy by fuel cells if necessary.

In the most common embodiment of the invention, the electrolysis cell is placed inside a pressure-resistant pressure shell, and from the hydrogen side of the electrolysis cell, hydrogen is passed through a pipe drawn through the wall of the pressure shell to a hydrogen reservoir. Oxygen from the electrolytic cell is allowed to enter the pressure shell. The oxygen pressure in the pressure shell is adjusted so that it remains constant with the pressure in the hydrogen reservoir. The pressure control can be implemented, for example, by discharging oxygen from the pressure shell through a valve obtained by means of the pressure of the hydrogen reservoir. Preferably, however, the oxygen is recovered and led to a separate oxygen tank, whereby oxygen is led from the pressure shell by means of a valve controlled by the pressure of the hydrogen storage in the oxygen tank.

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It is customary for the hydrogen gas from the electrolysis cell and the oxygen: *: gas to be first passed through water separators to separate the water entrained in the gases. In the apparatus according to the invention, the water separators can advantageously be placed inside the pressure shell, whereby the water separators do not have to be pressure-resistant. The water separators can also be placed outside the pressure shell if the water separators are equipped with a pressure-resistant shell.

In the water separators, the water separated from the gases is returned to the electro-30 lysis cell. According to a suitable procedure, the water from the hydrogen gas water separator is passed to the oxygen gas water separator, from where the water is returned to the electrolysis cell. The TållS hydrogen gas water separator can be equipped with level sensors that control a valve located in the water return line. As the surface rises to its upper height, the valve 35 opens and water can pass from the hydrogen gas water separator to the oxygen gas water separator. When the surface lowers to its lower height, the valve closes.

According to another embodiment of the invention, the pressure-resistant shell 5 is used for the storage of gases generated by myfis electrolysis. To prevent mixing of hydrogen and oxygen gases, the internal volume of the pressure shell must be divided into two different compartments by a non-shoveling membrane on the wall, one serving as a hydrogen storage and the other compartment containing an electrolytic cell acting as an oxygen storage.

The gas-impermeable membrane or layer is preferably thin and flexible, whereby it acts as a semi-automatic pressure regulator. Suitable film materials include e.g. non-shoveling plastics and metals.

Since hydrogen and oxygen are generated in the electrolysis cell in a volume ratio of 2: 1, the volumes of hydrogen storage and oxygen storage are preferably in the same ratio. In the case that the bellows shell operates at the same time as the gas tank, it is advantageous for the myOs storage that the volume of the hydrogen storage is approximately twice the volume of the oxygen storage.

The invention will be described in more detail below with reference to the accompanying figures, in which Figure 1 shows the basic structure of an electrolysis apparatus according to the invention with water separators located inside the pressure housing, Figure 2 shows an alternative embodiment with water separators located outside the pressure housing, and; Figure 3 shows an alternative in which the bellows shell also acts as a reservoir for the gases to be stored.

Figure 1 shows a pressure vessel 10 which acts as a pressure shell. An electrolytic cell 11 is arranged inside the shell 10 and is provided with an electrolyte inlet connection 12, hydrogen and oxygen outlet connections 14 and 13 and electric ignition lines 15, respectively.

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An electrolytic liquid, for example water, is introduced by gravity into the electrolytic cell 11. In the embodiment according to Figure 1, water separators 16 and 17 are shown for separating water from hydrogen and oxygen.

5 Water is supplied to the electrolytic cell 11 via a water line 18 and a pump 19 through a water inlet line 20 through the pressure shell 10 to an oxygen-gas water separator 17 and further thereafter via a water inlet line 21 and a non-return valve 22 to an inlet 11 and further to is passed through the oxygen outlet connection 13 and the oxygen outlet line 23 to the oxygen water separator 17. The water entrained with the oxygen gas separates in the water separator 17 and returns to the electrolysis cell 11 via the line 21. From the oxygen gas water separator 17, the oxygen discharge pipe 24 further leads to the interior of the pressure shell 10, whereby the pressure of the oxygen-15 gas prevails in the pressure shell 10.

The hydrogen gas generated in the electrolysis cell 11 is led through the hydrogen outlet connection 14 through the hydrogen outlet line 25 to the hydrogen gas water separator 16. From the water separator 16 to the hydrogen gas storage , whereby the water accompanying the hydrogen gas is returned to the electrolysis cell 11 as described above.

I '·'; 25: Oxygen gas is led from the interior of the pressure shell 10 to the oxygen removal line 32 and further to, for example, an oxygen tank (not shown). The oxygen removal line 32 is provided with a pressure sensor 33 and a valve 34. inside the pressure housing 10.

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The pressure control in the apparatus according to Fig. 1 can advantageously be carried out, for example, by connecting the pressure regulator 35 to the hydrogen and oxygen pressure sensors 26,33 via signal lines 36 and 37 and to the pressure regulator 35 according to the signal received from these pressure sensors 26,33. . 35 opens and closes through the signal line 38 the valve 34 in the oxygen removal line 32 to maintain the oxygen gas pressure at substantially the hydrogen storage pressure.

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Fig. 2 shows the apparatus according to Fig. 1 modified so that the hydrogen gas and oxygen gas water separators 16 and 17 are arranged outside the pressure shell 10. The water separators 16 and 17 are then of such a construction that they can withstand the maximum pressure prevailing in the system. The apparatus of Figure 2 is similar in other respects to the apparatus of Figure 1, except that the oxygen outlet pipe 10 39 is guided through the wall of the pressure shell 10 into its interior.

In the embodiment according to Figure 3, a pressure shell 10 is shown, which is divided by a flange connection 41 into a hydrogen reservoir 42 and an oxygen reservoir 43. Between the flanges 41 there is a flexible gas-impermeable membrane 44, 15 separating the hydrogen and oxygen reservoirs 42,43. An electrolysis cell 11 is placed inside the oxygen reservoir 43, from which oxygen is passed through line 23 to the oxygen gas water separator 17 and hydrogen is passed through line 25 to the hydrogen gas water separator 16, and sails 45 for adding water to the electrolysis cell 11 via line 46. The additional water in the tank 45 20 is led, for example, from the pipe 18 by means of a pump 19 and a line 20. In this case, the water core 45 is connected to the myds pipes 31,21 to return water from the hydrogen and oxygen water separators 16,17. The system may include an additional silicon or cylinder 47 for the hydrogen gas and an additional vessel or cylinder 48 for the oxygen gas to which the gases are passed from the hydrogen reservoir 42 and the oxygen reservoir 43 via line 49 and line 50, respectively.

The operation of the system is otherwise similar to that shown in Figure 1; except that hydrogen gas is conducted from the hydrogen gas water separator 16 to the hydrogen storage 42 via line 51 and oxygen is conducted from the oxygen gas water separator 17 to the oxygen storage 43 via line 52.

The above embodiments are intended to be illustrative only and not restrictive.

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Claims (7)

1. Electrolysis plant for the production of wet by probing electrolytic liquid to wet and oxygen by means of electric current in a closed 5 pressurized electrolytic cell (11) placed in a pressure shell (10), characterized in that a closed electrolytic cell (11) is placed in a pressure shell (10) which is kept in a pressurized state with the aid of the pressure of the oxygen formed in the electrolysis. 2. Electrolysis plant according to claim 1, characterized in that the oxygen formed in the electrolytic cell (11) is fed to the pressure plate (10) and the water is fed to a wet gas storage tank (29). 3. An electrolysis plant according to claim 1 or 2, characterized in that the pressure on the oxygen gas is maintained in the pressure plate (10), which pressure is substantially the same as the pressure prevailing in the gas line. Electrolysis system according to any one of the preceding claims, characterized in that the pressure shell (10) is divided by a membrane which is impervious to gas or with a wall (44) in a wet wire (42), where the wet formed in the electrolysis, and an oxygen supply (43) is directed to where the oxygen formed in the electrolysis is directed, and that the electrolytic cell (11) is placed in the oxygen supply (43). : 25 5. Electrolysis system according to claim 4, characterized by - that said impermeable membrane or wall (44) is made of metal and / or plastic. Electrolysis system according to any of the preceding claims, characterized in that the wet and oxygen formed in the electrolytic cell (11) are led to liquid separators (16 and 17) of which at least one or arc years are placed inside the pressure shell (10). : 35 10 90 568 7. Electrolysis plant according to any one of claims 1-5, characterized in that the wet formed in the electrolytic cell (11) and the oxygen are conducted to liquid separators (16 and 17), of which at least one or the arc is placed outside the pressure shell. (10). 5