Compact electrolyzer for the production of hydrogen

Description:

The invention relates to apparatus for electrolytic hydrogen generation, which can be used as secondary or alternative fuel for the internal combustion engines of automobile transport. The invention can also be used in the chemical and petroleum industries.

The closest solution is the electrolyzer for obtaining hydrogen which includes о capacity equipped with two cathodes in flow and two flat perforated anodes, a drain of gas in the form of dome and о source for maintaining the electrolyte level with connections and pump for recirculating it [1] . This electrolyser contains a diaphragm that separates the cathodic and anodic spaces, and the porous volumetric flow cathodes are made of fluffy carbonaceous material, which is unstable in the operating conditions of the plant, however, the operation of such an electrolyser is related to additional energy costs to the electrolysis to overcome the electrical resistance of the diaphragm, which separates the anodic and the cathodic space. The presence of the diaphragm diminishes the operating stability of the installation due to the low electrolyte stability under the electrolyte recirculation conditions.

The technical problem solved by the present invention consists in the decrease of the specific energy consumption for obtaining hydrogen due to the decrease of the electrical resistance of the system during the electrolysis, the increase of the efficiency of the process of electrolysis of the water to obtain the hydrogen, as well as the compactability and the durability of the electrolyser.

The problem is solved by the fact that the compact electrolyser for obtaining hydrogen includes a body with a central cathode flow compartment of a porous volumetric foam material with low-pressure nickel-rhenium chemical-catalytic coating with low release pressure of hydrogen, perforated anodes of a material with high voltage surge oxygen release and two electrolyte discharge connections, which communicate with the lower ends with о feeding capacity. The upper part of the body is executed as a dome-shaped lid connected with the о semi-annular chamber with hydrogen exhaust connection, which communicates with a channel with the flap located horizontally for the separation and evacuation of oxygen, executed from a diamagnetic material, also from the outside. to the channel on the side of the semi-ring chamber permanent magnets are placed, and the middle part of the channel is coated with о resistance coil in two sections with thermal insulation covering which form two arms of an unbalanced bridge, connected with resistors, an automatic potentiometer with a scale of oxygen percentage content and with о current source. The electrolyser is equipped with a metering device, a level meter feeder, as well as a о recirculation pump coupled with the feed capacity and the cathode compartment.

The technical result of the invention consists in that the exclusion of the separation diaphragms considerably reduces the electrical resistance in the system to the electrolysis of the water, which reduces the energy consumption during the electrolysis and, respectively, the specific consumption of electricity for obtaining electrolytic hydrogen. Execution of the electrodes from materials with low overvoltage and materials with high overvoltage facilitates the release of electrolytic hydrogen with the least concomitant release of oxygen, which due to the magnetic susceptibility separates and releases easily into the magnetic field. In case of violation of the electrolysis regime, at which it is possible to release small quantities of oxygen, at the same time it is possible to determine its quantity in the electrolytic gases and to regulate its removal with the help of the scraper.

This ensures the increase of the efficiency of the process and of the specific hydrogen output relative to the о unit of energy consumed, which facilitates the increase of the ergonomics of the hydrogen technology. At the same time, this conditions the increase of the electrolyzer compactness and the stability of the operation.

The invention is explained by means of the figure, which shows the scheme of the proposed electrolyzer.

The compact electrolyser for obtaining hydrogen includes a body 1 with a central cathode compartment 2 in flux from a porous volumetric foam material with low-voltage nickel-nickel chemical-catalytic coating and anodes 3 planes perforated from a high-voltage material oxygen release; two electrolyte outlet connections 10, which communicate with the lower ends with о supply capacity 7. The upper part of the body is executed as a dome-shaped lid 11, connected with the о semi-annular chamber 12 with hydrogen outlet 13, which communicates with a channel 14 with a flap 15 located horizontally for oxygen separation and evacuation, executed from a diamagnetic material. At the same time, from outside the channel 14, on the side of the semi-ring chamber are

MD 322 Z 2011.08.31 place permanent magnets 16, and the middle part of the channel is covered with о resistance coil in two sections R_ti and R_t2 with thermal insulation coating 17, which forms two arms of an unbalanced bridge, connected with resistors R3 and R4, adjustable transistor R5, automatic potentiometer 18 with a percentage oxygen content scale and with a current source 19. The electrolyser is equipped with a metering device 6, a feeder 4 with level meter 5, as well as a о recirculation pump 8 coupled with the feed capacity 7 and the cathode compartment via the inlet connection 9 of the electrolyte.

The lid 11 of the electrolyser, the semi-annular chamber 12 and the channel 14 are made of diamagnetic material. As electrolyte for electrolysis, distilled water or desaturated water with electroconductivity of 10 'is used.⁴ cm / m, in order to increase the electroconductivity of the electrolyte, solutions of 25 ... 30% KOH or 16 ... 20% NaOH are prepared with the possibility of adding sodium chromate in the amount of 2.5 ... 3 g / 1 . The role of the latter is oriented to the improvement of the functioning of the cathodes due to passivation of their surface and to exclude the discharge of charge on them of the compounds - impurities from electrolyte.

As a material for porous cathodes in flux 2, which are a variety of three-dimensional electrodes, foamed metals can be used, in particular, copper that is produced in the metallurgical industry by spraying inert gases in molten metal or by stimulating local gas formation upon introduction. of a gas-emitting reagent (e.g., TiH₂), due to which the cell structure is formed with open pores having the porosity coefficient of 0.92 ... 0.96.

In order to ensure a low voltage surge for the release of hydrogen on the surface of this electrode, a layer of homogeneous thickness of nickel-rhenium alloy of 5 ... 10 mm is deposited by the chemical-catalytic method. The known deposition technology ensures a high degree of homogeneity of the layer deposited in the inert volume of the pores of the foamed metal with cellular structure, ensuring electrocatalytic properties respectively to the surface of the electrodes. As a result, the special character of the microstructure on the surface of the foamed metal, and the presence of the reindeer in the nickel layer facilitates the decrease of the surge voltage -0,5-0,6 V, characteristic for the nickel layers up to -0,1-0,12 V for nickel-rhenium alloy.

As insoluble anodes 3, electrode graphite or titanium plated with ORTA-type ruthenium dioxide or OPTA-type iridium dioxide can be used, which have high values ​​of hydrogen overvoltage. but the latter is more stable and practically does not destroy itself in the process of electrolysis, due to which it ensures longer operation. The presence of holes in the construction of anodes not only ensures the mass exchange in the volume of the electrolyser, but also increases the diffusion capacity of the current at the electrolysis, which is favorable for the functioning of the entire system.

These properties of the materials of the cathodes and anodes lead to the fact that the process of electrolysis to electrodes runs in the field of potentials up to the release of oxygen, which facilitates the minimization of the released amount of it, while the release of hydrogen in the proposed electrolyzer will be maximum. This conditions the increase of the specific quantity of the hydrogen released during the electrolysis, the decrease of the energy consumption during the process and, respectively, the increase of the productivity of the process under flow conditions.

The electrolyzer works like this.

Inside the body 1 of the electrolyzer, through the metering device 6 is inserted the electrolyte up to the set level, determined by the height of the connections 10 and recorded by the meter 5. Then the recirculation pump 8 is included and is applied to the double cathode 2 and the anodes 3, initiating the process of electrolysis of the water, as a result on the cathode and in its pores, hydrogen is released in the form of gas, which is released from the flow electrolyte in the lid 11 of the electrolyzer, then in the semi-annular chamber 12, from which through the outlet 11 the hydrogen is directed for use.

On anodes 3, due to the overvoltage, the oxygen formation process is slowed down, it is possible to release oxygen in a small amount in the lid 11 of the electrolyzer together with the main amount of hydrogen in the semi-annular chamber 12.

When the current is connected to the source 19, the heating of the coiled platinum coil R takes place._ti and R_t2. If oxygen is lacking in the initial mixture, then there is no movement in the transverse channel. In the presence of oxygen in the initial mixture, its molecules orient in the magnetic field and are attracted to the channel, warming up to 100 ... 200 ° C. As the temperature increases, the magnetic susceptibility of oxygen decreases, which is why the new portions of cold gas are attracted to the magnetic field, pushing the heated oxygen into the chamber.

MD 322 Z 2011.08.31 semi-annual. The convex flow of gas mainly receives heat from coil R_tb As a result, the temperature in the sections becomes different.

According to the results of the measurement of resistance R_you and resistance R_t2, proportional to the concentration of the gas analyzed in the initial mixture, in the diagonal of the measurement of the bridge, which includes the continuous resistances R₃ and R4 and adjustable braid R₅, the imbalance signal appears, which is automatically fixed by the potentiometer 18 with a graduated scale in percent for the oxygen content, which is then evacuated from the system through the adjustable flap 15.

The process of electrolysis in the proposed electrolyser proceeds at 0 low voltage to the electrodes due to the reduced ohmic losses at low values ​​of the current density at 0 imitated by the active volumetric surface of the porous cathodes, which condition the possibility of reaching a large sum force of the current, necessary for the electrolysis, under these very intense conditions. As the electrolyte level decreases due to regular water consumption during electrolysis, the required amount is automatically added using the metering device 6, fitted with a hermetic lid and valve, through the connection located at the given electrolyte level. As the required level is reached, the outlet opening of the connection in the metering device 6 is closed and the water flow is interrupted until a new decrease of the electrolyte level, thus ensuring its maintenance at the given level.

Thus, it is ensured to reduce the energy consumption for obtaining hydrogen due to the decrease of the electrical resistance in the system, the increase of the efficiency of the water electrolysis process and the reliability of the electrolyser, at the same time it is possible to compact the construction.

(56) Bibliographic references cited in the description: