AT503432B1 - ENERGY SUPPLY METHOD FOR AN ELECTROLYSIS CELL - Google Patents

Description

2 AT 503 432 B1

The invention relates to a method for supplying an electrolytic cell with electrical energy for producing a gaseous product from a liquid medium by electrolysis, wherein the energy is obtained from a primary energy source, a device suitable for this purpose, further a method for producing a gaseous product from a liquid Electrolysis in an electrolytic cell in which a current flow is forced between at least two electrodes and a device provided for this purpose.

Hydrogen as an alternative energy source is becoming increasingly important, not least because of the ever-increasing price of crude oil products. The preparation is usually carried out by electrolysis of water. Today's common electrolysis cells still consume more electrical energy for the production of 1 m3 of hydrogen, despite the constant optimization, than is theoretically necessary. This is due to the high power loss. If hydrogen is burned in the sequence, it can recover about 3.5 kWh of energy, so that currently the energy balance is negative and thus the proportion of energy consumed from hydrogen in comparison to conventional energy sources is still negligible.

There are already known methods for reducing the power consumption in the electrolysis of water. These aim at the optimization of the cathode and anode material as well as at the optimization of the electrical parameters of the supply circuits of the electrolysis cell.

DE 197 15 690 A describes a generator which is particularly suitable for applications with slow drive sources, such as e.g. Wind turbines, free water wheels or tidal power plants. Due to the construction of the generator complex gears can be saved. It is without further transformation and thus lossless DC available, as it is e.g. in the electrolysis of water or in charging of accumulators is needed. When connecting to a public network, an inverter is connected downstream. In the generator, the number of coils in the rotor and stator can be the same and always have the same winding distance between the coils, so that a single DC pulse occurs and only until the coils meet again, the next pulse. In this variant, one may possibly do without capacitors on the stator coils. In a variant in which a different number of coils is arranged on the stator and the rotor, depending on the distribution, a smoothed DC voltage can be produced by overlapping the individual pulses. The overlap of the pulses results in a regular DC voltage. The downstream rectifiers / capacitors smooth the current pulses even further. This current can flow through an inverter and be fed with the appropriate frequency in a public network.

EP 0 362 445 A discloses a method for producing hydrogen by electrically conditioning electrodes, wherein the electrodes are arranged in an electrolyte and comprise a cathode and an anode. In this case, a pulsating DC signal is used with particular characteristics in terms of pulse width, peak voltage and duration between successive pulses of the signal, wherein values are selected such that upon application of the pulsating DC voltage signal to the electrodes during the interval between the pulses, where the potential of the anode section of the electrodes is positive with respect to the hydrogen standard potential and during the duration of each pulse, when the anode portion is made more positive than during the interval between the pulses, the anode portion of the electrode members is maintained substantially in a state of final passivation, the particular one Substantially no oxygen is generated at the anode portion and the anode portion is consumed during operation of the device and wherein the hydrogen is applied to the cathode portion of the electrode elements is generated quickly.

The object of the present invention is therefore to specify a method and a device with which the extraction of hydrogen from water can be carried out more economically. 3 AT 503 432 B1

This object of the invention is achieved in the method according to the invention in that the energy from the primary energy source is fed into a drive device, that further with the drive device at least one means for generating voltage pulses is driven, said device forms a separate electrical network with the electrolysis cell , which is separated from the primary energy source, and the voltage pulses are introduced into the electrolytic cell, further by the method for producing a gaseous product from a liquid after the supply of the electrolytic cell with electrical energy by the method according to the invention, regardless of the inventive device in which the primary energy source supplies power to a drive device, in which further a device for generating voltage pulses can be electrically connected to the electrolysis cell and electrically separated is arranged from the primary energy source, said device being connected on the drive side with the primary energy source, and by a device for producing a gaseous product from a liquid in which a device according to the invention is electrically connected to the electrodes for supplying the electrolytic cell with electrical energy.

The invention is based on the fact that it was recognized that in a water electrolysis after the electrical separation of the electrolysis cells from the mains, the electrolysis continues for some time. In previously known electrolysis cells, the power network of the cell is connected to the overall network, so that measuring devices that measure the parameters of the cell during electrolysis, not only the size of the DC potential, ie that potential which prevails at the beginning of operation and the average value of the resulting current is taken into account , In such a power supply system, the meters do not take into account the amount of voltage required to recharge the cell due to power consumption, but the total value of the equipotential which, as the inventors found, is 10 to 15 times the potential required to recharge the cell is. All previously known optimization variants of such a power supply method are affected by it. On the other hand, with the method according to the invention, the amount of energy supplied by the voltage pulses, which is required for maintaining the same potential, is replenished. The power loss of the cell can thus be reduced. By the electrical separation of the cell from the primary energy source, for example the power grid, the measurement of the consumption of energy in the cell itself is possible regardless of the aforementioned sizes.

The device for generating the voltage pulses and the drive device are operated at the same speed, so that the power loss of the drive device can also be minimized.

According to a preferred embodiment, it is provided that the voltage pulses, which are introduced into the electrolytic cell, have a steeply rising and a gently sloping edge. It can thus be the energy deficit due to the consumption in the cell degraded very quickly, on the other hand so that the electrodes given enough time to restore the DC potential.

Voltage pulses can be used whose amplitude is greater by a value than the potential between the electrodes selected from a range with a lower limit of 5% and an upper limit of 25%, whereby not only a higher stability of the cell is achieved but also the continuity of gas production can be made uniform.

The voltage pulses may further have a pulse duration selected from a range having a lower limit of 0.5 ms and an upper limit of 10 ms, thereby allowing further reduction in power consumption.

It is advantageous if a pulse frequency of the voltage pulses is used, which is selected from a range with a lower limit of 100 Hz and an upper limit 4 Hz.

Similarly, voltage pulses may be used with an average amplitude selected from a range having a lower limit of 30V and an upper limit of 50V.

By these measures, a further increase in efficiency, i. the efficiency of the method or the device possible.

The drive device may be an electric motor or an internal combustion engine, whereby a sufficient stability of the power supply device is achieved.

Preferably, the electric motor is designed as a so-called single-phase motor, whereby a fine-tuning of the speed is made possible.

The device for generating voltage pulses is preferably a magnetic inductor, but may also be a pulse generator, wherein the efficiency can be increased by the use of the magnetic inductor. For the compactness of the device, it is advantageous if both the drive device and the device for generating voltage pulses are arranged in a common housing.

To increase the efficiency of the device, the magnetic inductor has an armature comprising a material having a high coercive force of at least 300 Oe. Here, the coercive force may be selected from a range having a lower limit of 300 Oe and an upper limit of 15 kOe.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each shows in a schematically simplified representation:

Fig. 1 is a schematic representation of the device for power supply;

2 shows a circuit diagram for measuring the electrical quantities in the experimental verification of the method according to the invention;

3 shows a possible course of the voltage applied to the electrodes;

4 shows the experimental dependence of the change in the specific power on the number of cells used;

Fig. 5 shows the dependence of the specific power on the voltage at the cell.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions. All statements on ranges of values in the description of the present invention should be understood to include any and all sub-ranges thereof, e.g. the indication 1 to 10 should be understood to mean that all subregions are included, starting from the lower limit 1 and the upper limit 10 AT 503 432 B1, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

1 shows a device 1 for supplying electrodes 2 of an electrolysis cell 3 with electrical energy. This device 1 comprises a primary energy source 4, which supplies power to a drive device 5, furthermore a device 6 for generating voltage pulses, which is electrically conductively connected to the electrodes 2 of the electrolytic cell 3 via lines 7.

The primary energy source 4 is formed in the present embodiment of FIG. 1 by the power grid. This power supply supplies the drive device 5 designed as an electric motor.

Instead of the power grid or the electric motor can be used as the primary energy source 4 and a hydrocarbon mixture, which is kept in stock in a tank and with which an internal combustion engine is driven as drive means 5.

As an electric motor, all known from the prior art electric motors can be used, for example polyphase electric motors, asynchronous motors, etc. Preferably, however, a so-called single-phase motor is used.

The device 6 for generating the voltage pulses is preferably formed by a magnetic inductor. This magnetic inductor has at least one winding and an armature which is surrounded by the winding. The movement of the magnetic inductor generates the voltage pulses.

In the electrolysis cell 3 according to FIG. 1, only two electrodes 2 are arranged. However, it is possible to arrange more than two electrodes 2, in which case each electrode pair forms a subcell of the electrolytic cell 3.

As can be seen from Fig. 1, the means 6 for generating the voltage pulses is arranged electrically separated from the drive means 5, in other words, electrically separated from the primary power source to the power grid.

In a preferred embodiment, both the drive device 5 and the device 6 for generating the voltage pulses are arranged in a common housing 8.

The drive device 5 sets the armature of the magnetic inductor in motion. For the transmission of the rotational movement of the drive device 5, a common shaft 9 is connected to the device 6 for generating the voltage pulses. This shaft is stored for example in bearings 10, which are arranged on the housing 8.

Although the common shaft 9 is the preferred embodiment, it is of course possible to provide other transmission means for the rotational movement, for example with V-belts or toothed wheels or chain wheels with chains.

In the preferred application, water is contained in the electrolysis cell 3 in order to recover hydrogen and oxygen from it by the electrolysis. For this purpose, the electrolytic cell 3 is substantially encapsulated in relation to the environment and are provided only outputs for gas sampling in a storage container 11. If intermediate storage of the hydrogen is not desired, the device 1 according to the invention can also be part of a larger system, for example a combustion device, in order to obtain heat energy from the hydrogen. Likewise, the hydrogen can be used for various chemical reactions, for example hydrogenations, etc., so that the device 1 can also be part of chemical plants.

It is thus a low-cost on-site production of the required means of production allows.

In order to start the electrolysis, it is therefore sufficient to connect the drive device 5, for example, to the power supply, so that, by the rotation of the electric motor, the magnetic inductor, i. whose armature is rotated and thus the electrical energy generated in the form of voltage pulses is fed into the electrolysis cell 3.

The electrolysis cell 3 is operated with direct current. In the event that this is not available, a rectifier 12 is arranged in the device 1, which is formed according to the prior art. The rectifier 12 may be disposed between the means 6 for generating the voltage pulses and the electrolytic cell 3, as shown in FIG. 2 can be seen.

From Fig. 2 it is also apparent that for transforming the mains voltage in the device 1, a transformer 13 may be provided, which is arranged after the supply of electrical energy from the mains in the device 1.

When forming the drive device 5 as an internal combustion engine, the transformer 13 can be omitted.

In principle, all electrodes 2 suitable for electrolysis and known from the prior art can be used as electrodes 2. For the experimental setup in Fig. 2, with which the electrical parameters of the apparatus were determined, steel electrodes were used.

The experimental arrangement in FIG. 2 has an energy meter 14 in the flow direction downstream of the transformer 13, a wattmeter 15, in the circuit of the electrolytic cell 3, an ammeter 16 downstream of the rectifier 12, immediately before the supply of electrical energy , which is connected in series, a parallel-connected voltmeter 17, as well as an oscillograph 18 also connected in parallel.

With this experimental set-up it can be shown that once the operation of the device 1, i. the operation of the electrolytic cell 3, is recorded, this cell is charged to a so-called DC potential Up, as shown in FIG. 3 can be seen. The size of this potential increases with the number of individual subcells in the electrolysis cell 3.

According to the invention, it has been found that for a long-term operation of the electrolysis cell 3, it is sufficient to apply additional voltage pulses to these, or more simply to "recharge" them, it being advantageous if the amplitude of the voltage pulses increases the size of the direct potential Up by 5% to 25%, in particular 5% to 10%. The mean value of such a pulse can be 5 to 10% of the total sliding potential, depending on the pulse ratio and pulse length.

As already explained at the outset, the power grid of an electrolysis cell known from the prior art for the production of hydrogen is connected to the overall network, so that values are read on the devices which measure the absorption capacity of the electrolysis cell, in which the size of the direct potential and the mean value be taken into account in the resulting current. Thus, in such a power supply system, the meters do not take into account the magnitude of the voltage required to recharge the electrolytic cell, but the total value of the equipotential, which is 10 to 15 times the potential required to recharge the electrolytic cell. From the values of the experimental plant according to FIG. 2, it could be stated that the power formed by the drive device 5, 7, in particular the electric motor, and the device 6 for generating the voltage pulses, in particular a magnetic inductor, is equal to the product of Mean value of the voltage pulse and the average value of the current pulse is. This value is much lower than the product of the same potential and the average current value.

As is apparent from Fig. 3, it is advantageous if the voltage applied to the electrolytic cell 3, i. the course of the voltage across the electrodes 2 (Figure 1) is superimposed by voltage pulses having a steeply rising edge and a gently sloping edge. In essence, the voltage curve can therefore have an at least approximately sawtooth-shaped profile.

4 shows an experimental dependence 19 of the change in the specific power of the electrolytic cell 3 (W / l hydrogen-oxygen-gas mixture) on the number of subcells used for a magnetic inductor with a nominal power of approximately 4 W. Here, on the abscissa the number of subcells of the electrolytic cell 3 and plotted on the ordinate the specific power in W / l of the gas mixture. The experimental dependency is based on the readings of the voltmeter 17, which measures the potential 19 of the electrolytic cell 3, and the readings of the ammeter 16, which measures the mean value of the current flowing through the electrolytic cell 3 (Figure 2).

From this dependence 19 it can be seen that the specific power for obtaining the gas mixture remains the same with an increase in the subcells. It should be noted that this is a direct characteristic because it contains no power consumption of the transformation and rectification of the mains voltage, which accounts for about 30% of the stated dependence. Therefore, in a conventional prior art feeding method, the electric energy meter has a size of 5.8 W / L.

The experimental dependence 20 in FIG. 4 is based on the indications of the energy meter 14 and the wattmeter 15, corrected for the consumption for the idle of the magnetic inductor, which accounts for approximately 7% of the stated dependence. If the power consumption for rectifying the voltage induced by the inductor is taken into account, the displays of the oscilloscope 18 are located near the displays of the wattmeter 15 and the electric energy meter 14. In the method according to the invention or the device 1 according to the invention for supplying an electrolytic cell 3 with energy with four resp five subcells show voltmeter 17 and ammeter 16 about 4.5 W / l and the energy meter 14 about 2.0 W / l gas mixture.

With the number of subcells, the specific power for obtaining the gas mixture increases. This is because an increasing number of subcells increase the current in the stator coil and the reactive magnet current in the magnetic conductor of the inductor. This reduces the magnetic properties of the magnet of the armature. To increase the efficiency, it is therefore advantageous if an anchor is used with a high coercive force, in particular greater than 300 Oe or selected from a range of 300 Oe to 15 kOe.

Further experiments with the use of the magnetic inductor showed a minimum consumption of specific power in the electrolysis of water, as can be seen from FIG. As the subcell number changes, the magnitude of the voltage changes as it occurs, while the size of the minimum remains nearly unchanged.

Fig. 5 shows the dependence obtained with four subcells.

We have succeeded in maintaining the tension so precisely that the specific power was minimal in all repetitions of the same experiment. Nevertheless, in almost all series of experiments of five experiments, the specific performance readings were close to 1. For this reason, Fig. 4 shows the results of incomplete use of the available reserves to reduce the consumption of electrical energy for the water electrowater by means of magnetic inductor.

Thus, it could be proven experimentally that the energy consumption for water electrolysis can be reduced to about half compared to conventional cells.

The device 1 according to the invention is not only for the electrolysis of water, i. for the production of hydrogen gas and oxygen gas suitable, but there is a principle applicability for electrolysis cells 3, of course, frequency lengths and pulse ratios must be adjusted individually for each specific application. This is within the skill of the artisan, so that further discussion is unnecessary here.

The proposed method for reducing the electrical energy consumed by electrolysis cells 3 increases their energy efficiencies and reduces the cost of the gases obtained in the electrolysis of water oxygen and hydrogen.

It should be mentioned at this point that in principle the use of an electronically constructed pulse generator is possible. Preferably, this is constructed in a modular fashion, wherein in a first energy supply module, e.g. a transformer that is powered by the grid or other sources of energy, such as Accumulators, etc., fed electrical energy is galvanically separated from the terrestrial energy system. In the case of the AC power supply, if appropriate in a rectifier module, e.g. with conventional, known from the prior art rectifier elements, the floating rectification of the injected energy.

Wired to the power supply module or the rectifier module is a supply module, with which the continuous DC voltage is converted into a pulsating DC voltage ground. This pulsating DC voltage is subsequently fed to the electrolysis cell 3, i. on its anode and cathode.

For control and / or control, a control and / or control module is preferably provided, which is constructed from individual capacitors, transistors, at least one IGPT and, for example, in an embodiment variant in the form of a circuit board. With the help of this control and / or control module, for example, the control and / or control of pulse widths, pulse durations and the repetition frequency of the pulses is possible.

In this embodiment, the device 1 contains no drive device. Interestingly, however, the practical implementation has shown that the increase in efficiency is not present to a presumed extent, so that further development work has to be done in this regard.

The magnetic inductor may be so dimensioned that the pulse duration of the voltage pulses is selected from a range having a lower limit of 0.5 ms and an upper limit of 10 ms, and further, the pulse frequency is selected from a range having a lower limit of 100 Hz and an upper limit of 3000 Hz, as well as with an average amplitude of the voltage pulses, which is selected from a range with a lower limit of 1 V and an upper limit of 50 V. These values are particularly advantageous for the electrolysis of water.

The embodiments show possible embodiments of the device 1 for supplying an electrolytic cell 3 with electrical energy, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments are possible with each other and this Variability due to the teaching of technical action by objective invention in the skill of the field in this technical field

Claims (15)

9 AT 503 432 B1. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection. For the sake of order, it should finally be pointed out that, for better understanding of the structure of the device 1, these or their components have been shown partially unevenly and / or enlarged and / or reduced in size. The problem underlying the independent inventive solutions can be taken from the description. Above all, the individual in Figs. 1; 2; 3; 4; 5; shown embodiments form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures. Reference Designation 1 Apparatus 2 Electrode 3 Electrolysis cell 4 Primary energy source 5 Drive device 6 Device 7 Line 8 Housing 9 Shaft 10 Bearing 11 Storage container 12 Rectifier 13 Transformer 14 Energy meter 15 Wattmeter 16 Ammeter 17 Voltmeter 18 Oscillograph 19 Dependency 20 Dependence Claims: 1. Method for supplying an electrolysis cell (3) with electrical energy for the production of a gaseous product from a liquid medium by electrolysis, wherein the energy from a Primärärenergiequeile (4) is obtained and fed into a drive device (5), with the drive device (5) at least one device (6 ) is driven to generate voltage pulses, said means (6) with the electrolytic cell (3) forms its own electrical network that is separated from the primary energy source (3), characterized in that the voltage pulses in the electrolytic cell (3) ei be led, and that the means (6) for generating the voltage pulses and the drive means (5) are operated at the same speed. 10 AT 503 432 B1 2. The method according to claim 1, characterized in that voltage pulses are used with steeply rising and gently falling edge. 3. The method according to claim 1 or 2, characterized in that voltage pulses are used whose amplitude is greater by a value than that of the potential between the electrodes (2) which is selected from a range with a lower limit of 5% and an upper Limit of 25%. 4. The method according to any one of claims 1 or 3, characterized in that voltage pulses are used with a pulse duration selected from a range with a lower limit of 0.5 ms and an upper limit of 10 ms. 5. The method according to any one of claims 1 or 4, characterized in that voltage pulses are used with a pulse frequency selected from a range with a lower limit of 100 Hz and an upper limit of 300 Hz. 6. The method according to any one of claims 1 to 5, characterized in that voltage pulses are used with an average amplitude which is selected from a range having a lower limit of 30 V and an upper limit of 50 V. 7. A method for producing a gaseous product from a liquid, in particular water, by electrolysis in an electrolytic cell (3), wherein between at least two electrodes (2) a current flow is enforced, characterized in that the supply of the electrolysis cell (3) electrical energy according to a method according to one of claims 1 to 6 takes place. 8. Apparatus (1) for supplying electrodes (2) of an electrolysis cell (3) with electrical energy, with a primary energy source (4) which supplies energy to a drive device (5), with a device (6) for generating voltage pulses, which is electrically conductively connected to the electrolytic cell (3) connectable and electrically isolated from the primary energy source (4), said means (6) to the drive means (5) is connected on the drive side, characterized in that the drive means (5) and the device (6) for generating voltage pulses on a common shaft (9) are arranged. 9. Device (1) according to claim 8, characterized in that the drive device (5) is an electric motor or an internal combustion engine. 10. Device (1) according to claim 9, characterized in that the electric motor is a single-phase motor. 11. Device (1) according to one of claims 8 to 10, characterized in that the means (6) for generating voltage pulses is a magnetic inductor or a mechanical pulse generator. 12. Device (1) according to one of claims 8 to 11, characterized in that the drive device (5) and the device (6) for generating voltage pulses in a common housing (8) are arranged. 13. Device (1) according to claim 12, characterized in that the magnetic inductor comprises an armature comprising a material having a high coercive force of at least 300 Oe. 14. Device (1) according to claim 13, characterized in that the material of the armature has a coercive force selected from a range with a lower limit of 1 1 AT 503 432 B1 300 Oe and an upper limit of 15 kOe. 15. Device Production of a gaseous product from a liquid, in particular water, by electrolysis, with an electrolysis cell (3) in the at least two electrodes (2) are arranged, characterized in that for the supply of the electrolysis cell (3) with electrical energy Device (1) according to one of claims 8 to 14 is arranged electrically conductively connected to the electrodes (2). For this purpose 2 sheets of drawings