FI90570C - Process for controlling the pressure of an electrolysis device and electrolysis device for the production of hydrogen and oxygen - Google Patents

Description

90570

A method for controlling pressure in an electrolysis plant and an electrolysis plant for producing hydrogen and oxygen Fdrfarande fdr regiering av trycket i en electrolysanordning och elektrolysanordning fdr Produktion av våte och syre 5

The invention relates to a method for controlling a pressure in an electrolysis plant which produces hydrogen and oxygen by decomposing an electrolytic liquid 10 by means of an electric current. The invention relates to a myds electrolysis apparatus for producing hydrogen in a variable pressure electrolytic cell by decomposing the electrolytic liquid into hydrogen and oxygen by means of an electric current.

Hydrogen is an ideal and pollution-free energy source for special applications where no normal energy sources are available. Thus, for example, solar panels can be used to generate electricity in sparsely populated and hard-to-reach areas. Such facilities are often unmanned and require automatic or remote operation. Devices 20 must operate myds when sunlight is not available. Storing electricity in batteries alone would require a very large number of batteries, especially in northern latitudes, which are heavy and need maintenance.

25 The use of hydrogen as an energy store is another way of recovering the surplus energy produced by solar cells, whereby water is decomposed by means of electricity. . hydrogen and oxygen. If necessary, electricity can then be produced from the hydrogen by means of 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 pressure is required. Elektro-35 lyysikennon pressurization edellyttåå however, and working pressure difference between the hydrogen side and the oxygen side (i.e. the hydrogen side and the vedensyottdpuolen) electoral law is not formed, tu too large because many of the commercial electrolytic eivåt trans-structurally able to withstand high pressure differences. Especially muuttuvapaineiset 2 90570 solar cells produced såhkdå kåyttåvåt electrolytic paineensaatdjarjestelmia therefore need to ensure a pressure difference såilyttåmisestå the hydrogen and the oxygen side appropriate interval and a sufficiently low. In the known systems, the pressure transmission is usually realized by 5 electrically operated control valves, which consume electricity and are therefore not very autonomously suitable for hydrogen-producing systems with the aid of solar cells.

Esillaolevan keksinndn provides a method of pressure-saatåmi 10 into the electrolytic so that the pressure difference between the oxygen side and the hydrogen side is considered from A to present on certain value mechanically, whereby the control takes place automatically muuttuvapaineisessa jårjestelmåsså-ku luttamatta sahkbå.

Thus, the invention relates to a method for applying pressure in an electrolysis apparatus which produces hydrogen and oxygen by decomposing an electrolytic fluid by an electric current, the apparatus comprising a closed pressure electrolysis cell for generating hydrogen and oxygen from the electrolytic the electrolytic cell. The method according to the invention is characterized in that a certain pressure difference is maintained between the oxygen line pressure and the hydrogen line pressure by passing the oxygen leaving the system through one or more spring-loaded overflow valves so that the pressure in the hydrogen line is led to the spring side of the overflow valve.

The electrolytic liquid fed to the electrolytic cell contains water, but. . it may 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.

In the method according to the invention, mechanical non-consuming and automatically operating pressure supply is realized by applying a conventional overflow valve in a modified form. A normal overflow valve includes a metal diaphragm housed in a suitable housing which, under the pressure of a spring 3 90570 placed under the diaphragm, presses against the gas outlet of the gas reservoir, closing it. Only when the pressure of the gas or liquid exceeds the spring pressure does the flow vol pass through the outlet. In the method according to the invention for controlling the oxygen line pressure, the pressure of the hydrogen line 5 is led to the spring side of the overflow valve, whereby the pressure difference between the oxygen line and hydrogen line pressures automatically remains equal to the spring pressure. By adjusting the spring pressure, the pressure difference can be set to the desired value. At the same time, the diaphragm of the overflow valve prevents oxygen gas and hydrogen gas from coming into contact with each other.

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Thus edellåolevalla the automatic and without såhkåå functional sååtdjårjestelmå, which provides be interline can be realized, and working the oxygen and the hydrogen side automatically follow each other pressures size-shi said base plate, which can vary greatly depending on the hydrogen storage 15, the pressure in each of the variable måårååmåstå tyoskentelypai-medium.

A certain relatively small pressure differential yllåpitåminen oxygen and hydrogen side of the electoral law is necessary because of the structure and working of the electrolytic cell 20 can not withstand high pressure differences. Especially with the oxygen flow, large amounts of water are removed, which according to conventional technology can be separated from the gas using water separators and returned to the electro-lysis cell by gravity. With the hydrogen flow, a considerably smaller amount of water is removed, which can also be separated in the hydrogen gas separator. The water separated from the hydrogen gas can either be completely removed from the system or returned to the electrolysis cell. However, the latter option edellyttåå SITA, and working the hydrogen side of the condenser must be higher than the pressure in the oxygen side.

... 30 In the event that the water separated from the hydrogen gas is not recovered or returned directly to the electrolytic cell, the pressure in the oxygen line can be kept higher than the pressure in the hydrogen line. In this case, the hydrogen line pressure as such is applied to the spring side of the overflow valve in the oxygen line, whereby the spring pressure of the overflow valve takes care of ... Maintaining the pressure of the 35 oxygen line by a spring pressure higher than the hydrogen pressure by releasing excess oxygen out of the system.

4,90570

Siinå case, and working also separated hydrogen gas in the water to be pa-raft back to the electrolytic cell must therefore be interline, and working the hydrogen side of the water separator is at least somewhat higher than the pressure of the oxygen line and the same electrolytic cell sisååntulopuolella.

5 This can be done by applying to the spring side of the overflow valve in the oxygen line not the pressure of the hydrogen line as such, but reduced by a certain amount which is at least somewhat higher than the spring pressure of the overflow valve. Said reduced hydrogen pressure can thus be taken, for example, after a non-return valve 10 placed in the hydrogen line, which non-return valve drops the hydrogen line pressure by the desired amount. Nåin according to the procedure it is achieved, and working pressure of the hydrogen line remains higher than the oxygen line and the water side of the water separating hydrogen-times of, for example, can be returned to the oxygen side of the water separator and back to the electrolytic cell.

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According to a preferred embodiment of the method according to the invention, the hydrogen pressure on the spring side of the oxygen line overflow valve can optionally be taken either before or after the non-return valve, whereby the selection can be realized by means of a three-way valve 20, for example. The latter method is applied when the pressure after the non-return valve, i.e. the pressure in the hydrogen reservoir, is lower than the pressure in the hydrogen line. The former method is used when the pressure in the hydrogen line before the non-return valve is lower than after the non-return valve, for example when the pressures in the electrolysis plant are lowered and the pressure in the electrolysis cell is raised to the hydrogen storage pressure.

- - The three-way valve can advantageously also be replaced by using another one. ylivirtausventtiiliå. In this case, the spring side of the second overflow valve is; in connection with a point on the hydrogen line after the non-return valve and the spring side of the second overflow valve is in communication with the hydrogen-30 line before the non-return valve.

The invention also relates to an electrolysis plant for the production of hydrogen and oxygen. by decomposing the electrolytic fluid by means of an electric current, the apparatus comprising at least the following components: a) a closed pressure electrolytic cell for producing hydrogen and oxygen by an electric current, b) out of the interior of the electrolytic cell, and 10 d) input means for adding the electrolytic liquid to the electrolytic cell.

The electrolysis apparatus according to the invention is characterized in that the apparatus has means for maintaining a certain pressure difference between the oxygen line pressure and the hydrogen line pressure, which means engage one or more overflow valves in the oxygen line and means for directing the hydrogen line overflow valve.

Various embodiments of the production method and electrolysis apparatus according to the invention will now be described in more detail with reference to the accompanying figures, in which Figure 1 shows an electrolysis apparatus in which the oxygen gas pressure is kept higher than the hydrogen gas pressure. shows a modification of the apparatus of Figure 2, in which the three-way valve 30 is replaced by a second overflow valve, and; Fig. 4 shows an electrolysis apparatus in which the pressure of the hydrogen line to the spring side of the overflow valve is transmitted hydraulically.

Fig. 1 shows a variable pressure electrolytic cell 10 provided with an electrolytic liquid inlet 11, a hydrogen gas outlet 12 and an oxygen gas (oxygen / water mixture) outlet 13, as well as a power supply line 14. The correspondingly from oxygen gas.

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The electrolytic liquid is fed to the electrolytic cell 10 via a water line 17, a pump 18 and a water line 19 to an oxygen gas water separator 16 and from there on to the electrolytic cell 10 via a water supply line 20, a non-return valve 21 and an electrolytic liquid inlet.

The oxygen generated in the electrolysis cell and the water accompanying it are passed through the oxygen outlet connection 13 and the oxygen outlet line 22 to the oxygen water separator 16. The water entrained in the oxygen gas separates in the water separator 16 and returns to the electrolysis cell 10 via line 20 by gravity.

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The hydrogen gas generated in the electrolysis cell 10 is led through the hydrogen outlet connection 12 and the hydrogen outlet line 23 to the hydrogen gas water separator 15. In the water separator 15, the water separated from the gas is discharged through the pipe 24 and the valve 25.

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In addition, the apparatus according to Figure 1 has been applied to the pressure shell system disclosed in Finnish patent applications FI-923903 and FI-923904, which is kept pressurized with oxygen gas pressure. Thus, Fig. 1 shows a pressure shell 26 inside which the electrolysis cell 10 is placed. The pressure shell 26 is preferably filled with an inert liquid and the pressurization is preferably effected by passing a pipe 27 from the oxygen gas water separator 16 to the pressure shell 26. Thus, the pressure in the pressure shell 26 prevails. It should be noted, however, that the use of a pressure shell is in no way relevant to the invention.

30

Hydrogen gas from the water separator 15 is further led through a line 28 and a non-return valve 29 to a hydrogen reservoir 30. The line 28 is further provided with an outlet pipe 31 and a valve 32 for lowering the hydrogen pressure, for example for the maintenance of the electrolysis plant.

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Oxygen gas is conducted from the oxygen gas water separator 16 to the overflow valve 34 in the line 33. The overflow valve 34 comprises a housing 35 which is divided by a sealing membrane 36 into two compartments 37 and 38. Compartment 37 includes a seat 39 with an opening 40 and an opening 40 passage 41. Oxygen gas flows through line 33 to compartment 37 of overflow valve 34 and further through orifice 40 and passage 41 to oxygen outlet pipe 42. Second compartment 38 of overflow valve 34 includes a spring 43 supported at one end on the head of housing 35 and at the other end on membrane 36. Thus, the oxygen gas of the oles is allowed to flow through the opening 40 and the channel 41 to the oxygen outlet pipe 42 only in the case that its pressure exceeds a certain value. In addition to the operation of the overflow valve 34, it is essential that the compartment 38 containing the spring 43 is connected via line 44 to the hydrogen pressure, i.e. line 28.

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In the apparatus according to Figure 1, the pressure control operates as follows. The diaphragm 36 of the overflow valve 34 is subjected on one side to the pressure in the hydrogen line 28 and in addition to the pressure caused by the spring 43, which presses the diaphragm 36 against the edges of the opening 40 in the seat 39. Thus, oxygen 20 can flow into the outlet pipe 42 only when the oxygen pressure in line 33 is greater than the sum of the pressure in the hydrogen line 28 and the spring pressure in the spring 43. As the oxygen flows, the pressure in the oxygen line 33 decreases until it is at most one spring higher than the pressure in the hydrogen line 44 and 28, whereby the membrane 36 closes the opening 40.

: -: 25 Thus, the oxygen pressure automatically follows the pressure in the hydrogen line 28, however, always remaining higher than the hydrogen pressure in the line 28.

. . The advantages of the presented pressure supply system are above all that the output is mechanical and does not consume electric current, separate control valves and. . pressure sensors are not required and hydrogen cannot be consumed.

30

If it is desired to relieve the pressures from the electrolysis equipment as a pre-sensor::: for maintenance, the valve 32 in the outlet pipe 31 is opened and hydrogen is flowed out. In this case the pressure in line 44 decreases and the membrane 36 lets oxygen flow to the outlet pipe 42 . The check valve 29 eståå vetykaasusåilidn 30 • pressure discharge outlet pipe 31. The apparatus is again kåynnis- 8 90570 tettåessfl overflow valve 34 takes care be interline that the hydrogen pressure in line 28 before takaiskuventtiiliå 29 rises and and working the oxygen gas pressure in line 33 will rise at the same rate. reaches the hydrogen pressure in line 28 of the hydrogen storage 30 a pressure hydrogen gas begins to flow to hydrogen thief-5 toon 30.

As mentioned above, the stiffness of the spring 43 of the overflow valve 34 can be set to the desired value between the oxygen line pressure and the hydrogen line pressure. Although the absolute values of the pressures are in no way relevant to the operation of the equipment, it can be stated that an oxygen overpressure of the order of 1-2 bar is a suitable value in use.

The embodiment shown in Fig. 2 differs from Fig. 1 as follows. In this case 15, the water separated in the hydrogen gas water separator 15 is returned to the electrolysis cell 10 via the oxygen line water separator 16. Then the pipe 24 is connected to the oxygen line water separator 16.

For successful water recovery, the pressure on the hydrogen side must be higher than on the oxygen side. On the other hand, the operation of the oxygen flow-20 of the overflow valve 34 requires that the oxygen gas pressure in line 33 be greater than the sum of the spring pressure and the hydrogen pressure applied to the diaphragm 36.

, - The hydrogen pressure on the spring side of the overflow valve 34 is not derived from the inlet side of the non-return valve 29, but instead via the three-way valve 46 of the line 45 and 25 from the outlet side of the non-return valve 29. In addition, the non-return valve 29 is arranged to cause a pressure drop greater than the spring pressure of the overflow valve 34. Again, the absolute values of the pressures and pressure differences are not essential for the operation of the device, but a suitable spring pressure for the overflow valve; In addition, 34 may be of the order of 1-2 bar and the pressure drop in the non-return valve 29 may be of the order of 3-4 bar.

When it is desired to reduce the pressures in the apparatus according to Fig. 2 in the electrolysis plant, this is again done via the outlet pipe 31 and the valve line 35. Since the non-return valve 29 prevents the backflow, • * the hydrogen pressure on the spring side of the overflow valve 34 does not decrease and the oxygen pressure in the line 33 is not reduced. For this purpose, a line 47 is connected to the three-way valve 46, whereby the pressure on the spring side of the overflow valve 34 and the oxygen pressure, respectively, can be reduced via lines 44 and 47 with the connection via line 45 closed. Ko. the function can be implemented automatically if desired, iron pressure sensors (not shown) may be required in the hydrogen line 28 on either side of the non-return valve 29, whereby the three-way valve 46 can be arranged to operate automatically depending on whether the hydrogen reservoir pressure 30 is higher or lower than the pressure in line 28 before the non-return valve 29.

The apparatus of Fig. 3 is otherwise similar to the apparatus of Fig. 2 except that it includes two overflow valves 34a and 34b 15 to which hydrogen pressure is conducted from different sides of the check valve 29 on the hydrogen line 28. Hydrogen pressure is applied to the spring side of the first overflow valve 34a from after line 29. Hydrogen pressure is applied to the spring side of the second overflow valve 34b via line 47a from a point prior to check valve 20 29. Thus, the combination of overflow valves 34a and 34b replaces the three-way valve 46 and line 47 in the apparatus of Figure 2. When the hydrogen pressure before the non-return valve 29 is lower than after it, the oxygen pressure is controlled by the overflow valve 34b and when the hydrogen pressure before the non-return valve 29 is higher than after it, the oxygen pressure is controlled by the overflow valve 34a.

The apparatus of Figure 4 is similar in structure and operation to the apparatus of Figure 2 except that the hydrogen pressure overflows. to the spring side of the check valve 34 is transmitted hydraulically via line 44. In addition, a liquid-filled separator 48 is added to the line 44, which includes a sensitive but tight piston 49. In addition, the line 44 and the spring side 38 of the overflow valve 34 are liquid-filled. Separator: 48 then acts as a safety device in case the diaphragm 36 of the overflow valve 34 is broken and hydrogen and oxygen gases ... 35 came into contact with each other. When the diaphragm 36 ruptures, the piston 49 is depressed in its lower position by the seal 50 against the seal 90570, whereby the pressure connection from the hydrogen line 28 to the overflow valve 34 is closed and the mixing of the gases is prevented. A similar arrangement is, of course, also useful in the apparatus of Figures 1 and 3.

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Claims (14)

A method of controlling the pressure in an electrolysis plant which produces wet and oxygen by breaking down electrolytic fluid by means of electric current and which plant contains a closed pressurized electrolytic cell (10) to produce wet and oxygen, a wet line (23 , 28) for conducting moisture out of the electrolytic cell (10) to a wet supply (30), an oxygen line (22,33) for conducting oxygen from the electrolytic cell (10), and supply means (17,18,19,20,21) for supplying electrolytic fluid to the electrolytic cell (10), characterized in that a given pressure difference is maintained between the pressure of the oxygen line (33) and the pressure of the wet line (28) by passing the oxygen which leaches itself from the system via one or more spring loaded overflow valves. (34, 34a, 34b) in such a way that the pressure prevailing in the wet line (28) is directed to the spring side of the overflow valve (34, 34a, 34b). 2. A method according to claim 1, characterized in that a given overpressure or underpressure is maintained at the pressure in the wet line (28) in the oxygen line (33) by passing the wet pressure 20 to the spring side of the overflow valve (34,34a, 34b) from a steel bar after the check valve (29) in the wet line (28) or in a corresponding manner from a steel bar for the check valve (29). A method according to claim 1 or 2, characterized in that the given pressure difference between the pressure in the oxygen line (33) and the wet line (28) is maintained by using two overflow valves (34a, 34b) located in the oxygen line (33). , whereby to the spring side of one of the overflow valve (34b), the pressure in the wet line (28) is led from a steel leading to the check valve 30 (29) placed in the wet line (28) and to lead to the spring side of the understood Overflow valve (34a) the pressure from the wet line (28) from a stable one year after the check valve (29) placed in the wet line (28). 4. Electrolysis plant for producing wet and oxygen by breaking down electrolyte fluid with the help of electric current, which plant comprises at least the following components: le 90570 (a) a closed pressurized electrolytic cell (10) for producing wet and oxygen with the help of electric current; a wet line (23, 28) for discharging water from the interior space of the electrolysis cell (10) to a wet storage (30), c) an oxygen line (22, 33) for discharging oxygen from the interior space of the electrolysis cell (10). and 10 d) supply means (17,18,19,20,21) for supplying electrolytic fluid to the electrolytic cell (10), characterized in that the plant has means for maintaining a given pressure difference between the pressure in the oxygen line (33). and the pressure in the wet line (28), which means includes one or more overflow valves (34,34, a, 34b) located in the acid line (33) and means for directing the pressure of the wet line (28) to the spring side of the overflow valve (34,34a, 34b). 20 Installation according to claim 4, characterized in that the means for directing the pressure of the wet line (28) to the spring side of the overflow valve (34) contains a non-return valve (29) in the wet line (28) and a line (44,45,47 , 47a) to direct the pressure of the wet line (28) to the spring side of the overflow valve (34), 6. Installation according to Claim 5, characterized in that said line (44,47,47a) forms a connection from the spring side of the Sverstromflow valve (34) to a steel line in the wet line (28) for the check valve (29). Installation according to claim 5, characterized in that said line (44,45) forms a connection from the spring side of the overflow valve (34) to a stable in the wet line (28) after the check valve (29). 17. O 5 7 O 8. An installation according to claim 6 or 7, characterized in that it also includes a three-wave valve (46) for forming a spring connection (44,45,47) from the spring side of the overflow valve (34) to a steel in the wet line (28) which is before or after the check valve (29). 9. Electrolysis system according to any one of claims 4-8, characterized in that it contains two overflow fittings (34a, 34b) and lines (44,47a) to apply the pressure in the wet line (28) to the spring side of the overfill valves. (34a, 34b) in such a way that the spring side of one of the sword flow valve (34) is in contact with the steel in the wet line (28) before the check valve (29) and the spring side of the understand the overflow valve (34a) is in contact with the steel after the check valve ( 29) in the wet line (28). 15 An electrolysis plant according to any of claims 4-9, characterized in that the electrolytic cell is placed inside a liquid-filled protective shell (26) which is pressurized with the gas pressure formed in the electrolysis. 20 11. Electrolysis system according to claim 10, characterized in that the protective shell (26) is filled with inert liquid and pressurized with the pressure of the oxygen line (27,33). An electrolysis system according to any one of claims 4-11, characterized in that the gas volume of the wet line (23,28) between the electrolysis cell (10) and the check valve (29) in the wet line (28) is at least two, but preferably more than twice the size of the stream. the gas volume of the acid line (22,33) between the electrolysis cell (10) and the overflow valve (34) located in the acid line (33). Electrolysis system according to any one of claims 4-12, characterized in that the wet pressure to the spring side of the overflow valve is hydraulically formed by forming the liquid in the line (44). is 90570 14. Electrolysis system according to claim 13, characterized in that said line (44) contains a gas / liquid separator (48) provided with a piston (49), the piston (49) being connected to the spring side of the transverse flow valve (34) by the effect of the wet pressure, if the valve film (36) is