Electrolysis installations. Industrial hydrogen generators

Electrolysis is a chemical and physical phenomenon of the decomposition of substances into components through electric current, which is widely used for industrial purposes. Based on this reaction, units are manufactured to produce, for example, chlorine or non-ferrous metals.

The constant rise in prices for energy resources has made electrolysis plants for household use popular. What are such structures, and how to make them at home?

General information about the electrolyzer

An electrolysis installation is a device for electrolysis that requires an external energy source, structurally consisting of several electrodes that are placed in a container filled with electrolyte. This type of installation may also be called a water splitting device.

In such units the main technical parameter is productivity, which means the volume of hydrogen produced per hour and is measured in m³/h. Stationary units carry this parameter in the model name, for example, the SEU-40 membrane unit produces 40 cubic meters per hour. m hydrogen.

Other characteristics of such devices completely depend on the intended purpose and type of installation. For example, when carrying out electrolysis of water, the efficiency of the unit depends on the following parameters:

1. The level of the lowest electrode potential (voltage). For normal operation of the unit, this characteristic must be in the range of 1.8-2 V per plate. If the power source has a voltage of 14 V, then it makes sense to divide the capacity of the electrolyzer with the electrolyte solution into sheets into 7 cells. Such an installation is called a dry electrolyzer. A lower value will not start electrolysis, and a higher value will greatly increase energy consumption;

1. The smaller the distance between the plate components, the lower the resistance will be, which, when a large current passes, will lead to an increase in the production of gaseous substance;
2. The surface area of ​​the plates directly affects performance;
3. Heat balance and degree of electrolyte concentration;
4. Material of electrode elements. Gold is an expensive but ideal material for use in electrolyzers. Due to its high cost, stainless steel is often used.

Important! In constructions of a different type, the values ​​will have different parameters.

Water electrolysis plants can also be used for purposes such as disinfection, purification and water quality assessment.

Operating principle and types of electrolyzer

The simplest device has electrolyzers that split water into oxygen and hydrogen. They consist of a container with electrolyte into which electrodes are placed connected to an energy source.

The principle of operation of an electrolysis installation is that the electric current that passes through the electrolyte has a voltage sufficient to decompose water into molecules. The result of the process is that the anode produces one part oxygen, and the cathode produces two parts hydrogen.

Types of electrolyzers

Water splitting devices are of the following types:

1. Dry;
2. Flow-through;
3. Membrane;
4. Diaphragm;
5. Alkaline.

Dry type

Such electrolysers have the most simple design(picture above). They have an inherent feature, which is that manipulation of the number of cells makes it possible to power the unit from a source with any voltage.

Flow type

These installations have in their design a bath completely filled with electrolyte with electrode elements and a tank.

The operating principle of a flow electrolysis installation is as follows (from the picture above):

• during electrolysis, the electrolyte along with gas is squeezed out through pipe “B” into tank “D”;
• in container “D” the process of separating gas from the electrolyte takes place;
• gas exits through valve “C”;
• the electrolyte solution returns through tube “E” to bath “A”.

Interesting to know. This principle of operation is configured in some welding machines - the combustion of the released gas allows the elements to be welded.

Membrane type

The membrane-type electrolysis plant has a similar design to other electrolyzers, but the electrolyte acts as solid on polymer based, which is called a membrane.

The membrane in such units has a dual purpose - the transfer of ions and protons, the separation of electrodes and electrolysis products.

Diaphragm type

When one substance cannot penetrate and influence another, a porous diaphragm is used, which can be made of glass, polymer fibers, ceramics or asbestos material.

Alkaline type

Electrolysis cannot occur in distilled water. In such cases, it is necessary to use catalysts, which are alkaline solutions of high concentration. Accordingly, the bulk of electrolysis devices can be called alkaline.

Important! It is worth noting that using salt as a catalyst is harmful, since the reaction releases chlorine gas. An ideal catalyst would be sodium hydroxide, which does not corrode iron electrodes and does not contribute to the release of harmful substances.

Self-production of an electrolyzer

Anyone can make an electrolyzer with their own hands. For the assembly process of the simplest design, the following materials will be required:

• stainless steel sheet ( ideal options– foreign AISI 316L or domestic 03Х16Н15М3);
• bolts M6x150;
• washers and nuts;
• transparent tube - you can use a water level, which is used for construction purposes;
• several herringbone fittings with an outer diameter of 8 mm;
• plastic container with a volume of 1.5 l;
• a small filter that filters running water, for example, a filter for washing machines;
• water check valve.

Build process

Assemble the electrolyzer with your own hands according to the following instructions:

1. The first step is to mark and further cut the stainless steel sheet into equal squares. Sawing can be done at an angle grinder(Bulgarian). One of the corners in such squares must be cut at an angle to properly fasten the plates;
2. Next, you will need to drill a hole for the bolt on the side of the plate opposite to the corner cut;
3. The connection of the plates must be done alternately: one plate on “+”, the next on “-” and so on;
4. Between differently charged plates there must be an insulator, which acts as a tube from the water level. It must be cut into rings, which should be cut lengthwise to obtain strips 1 mm thick. This distance between the plates is sufficient for efficient gas release during electrolysis;
5. The plates are fastened together using washers in the following way: a washer is placed on the bolt, then a plate, then three washers, then a plate, and so on. The positively charged plates are arranged as mirror images of the negatively charged sheets. This allows you to prevent the sawed edges from touching the electrodes;

1. When assembling the plates, you should immediately insulate them and tighten the nuts;
2. Also, each plate must be ringed to make sure there is no short circuit;
3. Next, the entire assembly needs to be placed in a plastic box;
4. After this, you need to mark the places where the bolts touch the walls of the container, where you drill two holes. If the bolts do not fit into the container, they must be trimmed with a hacksaw;
5. Next, the bolts are tightened with nuts and washers to seal the structure;

1. After these manipulations, you will need to make holes in the lid of the container and insert fittings into them. In this case, tightness can be ensured by sealing the seams with silicone-based sealants;
2. The protective valve and filter in the design are located at the gas outlet and serve as a means of controlling its excessive accumulation, which can lead to disastrous consequences;
3. The electrolysis plant has been assembled.

The final stage is testing, which is carried out as follows:

• filling the container with water to the level of the mounting bolts;
• connecting power to the device;
• connecting a tube to the fitting, the opposite end of which is lowered into the water.

If a weak current is applied to the installation, the release of gas through the tube will be almost imperceptible, but it can be observed inside the electrolyzer. Raising electricity By adding an alkaline catalyst to water, you can significantly increase the yield of the gaseous substance.

The manufactured electrolyzer can act integral part many devices, such as a hydrogen torch.

Knowing the types, main characteristics, structure and operating principle of electrolysis plants, it is possible to carry out correct assembly homemade design, which will be an indispensable assistant in various everyday situations: from welding and saving vehicle fuel consumption to the operation of heating systems.

Video

Currently in Russia everything large quantity water supply and sewerage facilities, as well as production facilities, refuse to use commercial liquid chlorine and hypochlorites, opting for organizing their own synthesis of the necessary reagents directly at the facilities of use.

Production requires sodium chloride (salt), water, and electricity.

Reasons for such refusal:

1. Liquid chlorine is very dangerous.

Despite the low cost of chlorine, the activities and costs associated with its use greatly complicate and increase the cost of the entire production process.

2. Commercial sodium hypochlorite (GPHC 19%) is very expensive.

The cost of 1 ton of grade A GPHN does not exceed 20-30 thousand rubles. However, the amount of sodium hypochlorite equivalent to 1 ton of chlorine is already 100-150 thousand rubles. (since hypochlorite contains only 15-19% active chlorine and tends to further decompose).

Advantages of electrolysis equipment:

• waiver of costs for ensuring safety during transportation and storage;
• During the operation of electrolysis equipment, accidents associated with leakage are impossible large quantities reagent. Objects of operation of electrolysis plants for the synthesis of chlorine reagents do not belong to hazardous production facilities and are not included in the corresponding register;
• independence from the supplier - the reagent is produced in required quantity, productivity is regulated, which increases the energy efficiency of the facility;
• cheap raw materials - the cheapest technical salt can be used for synthesis. This will require the installation of additional equipment for purifying the saline solution entering the electrolysers, however, these costs are recouped in less than 1 year due to significant savings on raw materials;
• the resulting reagent is cheaper than the commercial one;
• for water supply facilities that use UV installations as the main method of disinfection - when introducing UV equipment, it is impossible to completely abandon the use of chlorine reagents, since it is necessary to ensure the sanitary condition of structures and networks, as well as the safety of water transportation to the consumer. Electrolysis plants together with UV equipment completely satisfy the need for chlorine, while the facility is excluded from the register of hazardous production facilities.

Electrolysis plants produce different reagents:

• chlorine or chlorine water (Aquachlor, Aquachlor-Bekhoff, Aquachlor-Membrane/Diaphragm);
• combined disinfectant with increased efficiency– a solution of oxidants containing chlorine, chlorine dioxide, ozone (Aquachlor, Aquachlor-Bekhoff);
• low-concentrated HPCN 0.8% (LET-EPM, Aquachlor, Aquachlor-Beckhoff);
• highly concentrated HPCN 15-19% (Aquachlor-Membrane/Diaphragm).

All these reagents are suitable for water disinfection purposes. The only limitation is the pH of the water being disinfected at the point of entry of the reagent - for water with a pH above 7.5, it is recommended to use chlorine water instead of hypochlorite, which is ineffective in an alkaline environment.

Let us dwell in more detail on each type of equipment of LET LLC:

Aquachlor and Aquachlor-Beckhoff:

• the resulting reagent has increased efficiency;
• individual modules have low performance. This allows you to respond flexibly to
• reagent requirement. The optimal performance of the complex is up to 250-500 kg of active chlorine per day;
• frequency of reactor replacement – ​​once every 3-5 years;
• ease of maintenance.

LET-EPM:

• unlimited productivity of complexes;
• ease of operation and low requirements for the quality of raw materials;
• frequency of replacement (recoating) of the electrode block – once a year;
• The reagent is suitable for most objects.

Aquachlor-Diaphragm:

• the possibility of obtaining chlorine water and concentrated HPCN 19%, as well as the simultaneous production of these reagents;
• the frequency of replacement of the electrode coating and diaphragm is no more than once every 10 years;
• high requirements for the quality of the saline solution;
• possibility of washing the diaphragm and returning to work in case of contamination saline solution inadequate quality;

Aquachlor Membrane:

• unlimited productivity of the complex (but not less than 50-100 kg/day);
• the possibility of obtaining chlorine and concentrated HPCN of 19% high purity, suitable for synthesis;
• the frequency of replacement of the electrode coating and membrane is no more than once every 10 years;
• very high requirements for the quality of the saline solution;
• if the membrane is dirty, it must be replaced with a new one;
• Equipment maintenance requires qualified personnel.

Cost of the final product (ascending, from least to highest):

• Aquachlor-Diaphragm
• Aquahdlor-Membrane
• Aquachlor/Aquachlor-Beckhoff
• LET-EPM

At one time, using electrolysis from molten salts, it was possible for the first time to isolate pure potassium, sodium and many other metals.

Today this process is also used in everyday life - to “extract” hydrogen from water. The technology is more than accessible, because a device for water electrolysis is just a container with a soda solution in which electrodes are immersed.

The electrodes are small square sheets cut from galvanized steel or, better, from stainless steel grade 03Х16Н15М3 (AISI 316L). Ordinary steel will be “eaten up” very quickly by electrochemical corrosion.

Having cut a hole in the wall of the container with a knife, you need to install two coarse filters on it - “mud filters” (the second name is an oblique filter) or filters from washing machines will do.

Next, a 2.3 mm thick board and a bubble tube are installed.

The creation of the electrolyzer is completed by installing a nozzle with a shutter located on the board side.

Top container device

The electrodes are made of stainless steel sheet measuring 50x50 cm, which must be cut into 16 equal squares with a grinder. One corner of each plate is trimmed, and in the opposite corner a hole is made for an M6 bolt.

One by one, the electrodes are put on the bolt, and the insulators for them are cut from a rubber or silicone tube. Alternatively, you can use a tube from the water level.

The container is fixed using fittings and only after that the bubble tube and electrodes with terminals are installed.

Bottom container model

In this version, the assembly of the device begins with a stainless base, the dimensions of which must correspond to the dimensions of the container. Next, install the board and tube. Installation of filters is not required in this modification.

Then you need to attach the shutter to the bottom board with 6mm screws.

The nozzle is installed using a fitting. If you nevertheless decide to install filters, then plastic clips with rubber gaskets should be used to secure them.

Finished device

The thickness of the insulators between the electrode plates should be 1 mm. With such a gap, the current strength will be sufficient for high-quality electrolysis, at the same time, gas bubbles can easily break away from the electrodes.

The plates are connected to the poles of the power source alternately, for example, the first plate to the “plus”, the second to the “minus”, etc.

Device with two valves

The manufacturing process of a 2-valve electrolyzer model is not particularly complicated. As in the previous version, assembly should begin by preparing the base. It is made from steel sheets, which need to be cut in accordance with the dimensions of the container.

The board is firmly attached to the base (we use M6 screws), after which you can install a bubbling tube with a diameter of at least 33 mm. Having selected the valve for the device, you can begin installing the valves.

Plastic container

The first one is installed on the base of the pipe, for which it is necessary to secure a fitting in this place. The connection is sealed with a clamping ring, after which another plate is installed - it will be needed to fix the shutter.

The second valve should be mounted on the pipe with a distance of 20 mm from the edge.

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Three valve models

This modification differs not only in the number of valves, but also in the fact that the base for it must be especially strong. The same stainless steel is used, but of greater thickness.

The location for installing valve No. 1 must be selected on the inlet pipe (it is connected directly to the container). After this, the top plate and the second bubble-type tube should be secured. Valve No. 2 is installed at the end of this tube.

When installing the second valve, the fitting must be secured with sufficient rigidity. You will also need a clamp ring.

Ready-made hydrogen burner

The next stage is the manufacture and installation of the valve, after which valve No. 3 is screwed to the pipe. It must be connected to the nozzle using studs, while insulation must be ensured using rubber gaskets.

Water in pure form(distilled) is a dielectric and in order for the electrolyzer to work with sufficient productivity, it must be turned into a solution.

The best performance is demonstrated not by saline, but by alkaline solutions. To prepare them, you can add baking soda or caustic soda to the water. Some remedies will also work household chemicals, for example, "Mr. Muscle" or "Mole".

Device with galvanized plate

A very common version of the electrolyser, used mainly in heating systems.

Having selected the base and container, they connect the boards with screws (4 of them will be needed). Then an insulating gasket is installed on top of the device.

The walls of the container should not be electrically conductive, that is, made of metal. If there is a need to make the container highly durable, you need to take Plastic container, and place it in the same sized metal shell.

All that remains is to screw the container with pins to the base and install the shutter with terminals.

Model with plexiglass

Assembling an electrolyzer using plexiglass blanks cannot be called a simple task - this material quite difficult to process.

Difficulties may also arise at the stage of finding a container of a suitable size.

One hole is drilled in the corners of the board, after which the installation of the plates begins. The step between them should be 15 mm.

On next stage proceed to installing the shutter. As with other modifications, rubber gaskets should be used. You just need to take into account that in this design their thickness should be no more than 2 mm.

Model on electrodes

Despite the slightly alarming name, this modification of the electrolyzer is also quite accessible to self-made. This time, assembly of the device begins from the bottom, strengthening the shutter on a solid steel base. The container with electrolyte, as in one of the options described above, will be placed on top.

After the shutter, the installation of the tube begins. If the size of the container allows, it can be equipped with two filters.

• the sheet does not touch the container;
• the distance between it (sheet) and the clamping screws should be 20 mm.

With this design of the hydrogen generator, the electrodes should be attached to the gate, placing the terminals on the other side of it.

Application of plastic gaskets

The option of manufacturing an electrolyzer with polymer gaskets allows you to use an aluminum container instead of a plastic one. Thanks to the gaskets, it will be reliably insulated.

When cutting out plastic gaskets (4 pieces are needed), you need to give them the shape of rectangles. They are laid in the corners of the base, providing a gap of 2 mm.

Now you can start installing the container. To do this, you will need another sheet in which 4 holes are drilled. Their diameter must correspond to the outer diameter of the M6 ​​thread - these are the screws that will be used to secure the container.

The walls of an aluminum container are stiffer than those of a plastic container, so for more reliable fastening, rubber washers should be placed under the heads of the screws.

Remains The final stage– installation of the gate and terminals.

Two-terminal model

Attach a plastic container to a base made of steel or aluminum sheet using cylinders or screws. After this you need to install the shutter.

This modification uses a needle nozzle with a diameter of 3 mm or slightly larger. It needs to be installed in its place by connecting to the container.

Now, using conductors, you need to connect the terminals directly to the bottom board.

The last element is to install the tube, and the place where it is connected to the container must be sealed with a clamping ring.

Filters can be borrowed from broken washing machines or regular “dirt collectors” can be installed.

You will also need to attach two valves to the spindle.

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Schematic representation

A schematic description of the electrolysis reaction will take no more than two lines: positively charged hydrogen ions rush to the negatively charged electrode, and negatively charged oxygen ions flow to the positive one. Why instead of clean water Do you have to use an electrolytic solution? The fact is that a fairly powerful electric field is required to break a water molecule.

A salt or alkali does much of this work chemically: a metal atom having positive charge, attracts negatively charged hydroxyl groups OH, and an alkaline or acidic residue that has a negative charge attracts positive hydrogen ions H. Thus, the electric field can only pull the ions away to the electrodes.

Electrolyzer circuit

Electrolysis takes place best in a solution of soda, one part of which is diluted in forty parts of water.

The best material for electrodes, as already mentioned, is stainless steel, but gold is best suited for making plates. The larger their area and the higher the current, the greater the volume of gas will be released.

Gaskets can be made from various non-conductive materials, but polyvinyl chloride (PVC) is best suited for this role.

Conclusion

The hydrogen it produces can be converted into fuel for cooking, or enriched with it in the gas-air mixture, increasing the power of car engines.

Despite the simplicity fundamental structure devices, craftsmen learned to make whole line its varieties: the reader can make any of them with his own hands.

Video on the topic

Electrolysis- This is the splitting or purification of substances under the influence of electric current. This is a redox process, on one of the electrodes - the anode - an oxidation process occurs - it is destroyed, and on the cathode - a reduction process - positive ions - cations - are attracted to it. During electrolysis, electrolytic dissociation occurs - the breakdown of the electrolyte (conducting substance) into positively and negatively charged ions (several degrees of dissociation are distinguished). When the current is turned on, electrons move from the anode to the cathode, and the electrolyte solution may become depleted (if it is involved in the process), it needs to be constantly replenished. The oxidizing anode can also dissolve in an electrolyte solution - then its particles acquire a positive charge and are attracted to the cathode.

The anode is a positively charged electrode - oxidation occurs on it
The cathode is a negatively charged electrode - reduction occurs on it
Based on the principle that unlike charges attract, along with this comesseparation or purification of a substance.

The material of the electrodes may be different, depending on the ongoing process. The mass of the substance that is obtained during electrochemical interaction is determined by Faraday’s laws and depends on the charge (the product of the current strength and the time the current flows), also depends on the concentration of the electrolyte and the activity of the materials from which the electrodes are made. Anodes can be inert - insoluble, do not react, and active - they themselves participate in the interaction (they are used much less frequently).

For the manufacture of anodes, graphite, carbon-graphite materials, platinum and its alloys, lead and its alloys, and oxides of some metals are used; Titanium anodes with an active coating of a mixture of ruthenium and titanium oxides, as well as platinum and its alloys, are used.

Insoluble anodes are compositions based on tantalum and titanium, special varieties of graphite, lead dioxide, magnetite. Steel is usually used for cathodes.

The following types of electrolytes can be used for the process: aqueous solutions of salts, acids, bases; non-aqueous solutions in organic and inorganic solvents; molten salts; solid electrolytes. Electrolytes come in varying degrees of concentration.

Depending on the purposes of electrolytic reactions, various combinations of types of anodes and cathodes are used: horizontal with a liquid mercury cathode, with vertical cathodes and a filtering diaphragm, with a horizontal diaphragm, with a flow electrolyte, with moving electrodes, with bulk electrodes, etc. Most processes tend to use products produced at both the anode and cathode, but usually one of the products is less valuable.

Electrolysis is widely used in industry; it is also used in medicine and the national economy.

Main applications of electrolysis:

• Water purification for use in the national economy,
• Wastewater treatment of used water from chemical plants.

To obtain substances and metals without impurities:

• Metallurgy, hydrometallurgy - for the production of aluminum and many other metals - aluminum from the melt of aluminum oxide in cryolite, electrolysis produces magnesium (from dolomite and sea water), sodium (from rock salt), lithium, beryllium, calcium (from calcium chloride), alkaline and rare earth metals.
• IN chemical industry electrolysis produces such important products such as chlorates and perchlorates, persulfuric acid and persulfates, potassium permanganate,
• Electrolytic separation of metal - electroextraction. The ore or concentrate is converted into a solution using certain reagents, which, after purification, is sent for electrolysis. This is how zinc, copper, and cadmium are obtained.
• Electrolytic refining. Soluble anodes are made from metal; impurities contained in the rough metal of the anode fall out in the form of anode sludge (copper, nickel, tin, lead, silver, gold) during electrolysis, and pure metal is released at the cathode.
• In electroplating - electroplating - producing coatings on metals that improve their operational or decorative properties and galvanoplasty - producing exact metal copies of any objects;
• To obtain oxide protective films on metals (anodizing); electrochemical processing is also used for polishing the surface of products and coloring metals,
• There is electrochemical sharpening cutting tools, electropolishing, electromilling,
• Electrolysis is also widely used in radio engineering.

Emit electrolysis aqueous solutions and molten media, as well as the production of electrochemical current sources themselves - batteries, galvanic cells, accumulators, the functionality of which is restored by passing current in the direction opposite to that in which the current flowed during discharge.

Main types of electrolysis plants:

• Installations for the production and refining of aluminum;
• Electrolysis installations for ferrous production;
• Electrolyzers for nickel-cobalt production;
• Installations for magnesium electrolysis;

• Copper electrolysis (refining) installations;
• Installations for applying galvanic coatings;
• Electrolysis plants for chlorine production;

• Electrolyzers for water disinfection.
• Electrolyzers producing hydrogen for nuclear power plants... etc.

Oxygen is a byproduct of many redox reactions.

During electrolysis, the current strength, its frequency and voltage, even polarity are regulated; these parameters control the speed and direction of the processes. The electrolysis reaction is always carried out at constant current, since the constancy of the poles is very important here. In very rare cases, when polarity is not significant, alternating current is used (for example, during electrolysis of gases).

Based on the design of the cathode device, modern aluminum electrolyzers are divided into

• Electrolyzers with and without bottom,
• With stuffed and block hearth;
• according to the current supply method: with one-sided and two-sided busbar circuit;
• according to the method of gas capture: electrolyzers open type, with a bell gas suction and covered type.

The unsatisfactory properties of all existing designs of aluminum electrolyzers include an insufficiently high energy utilization factor, a short service life and insufficient efficiency of exhaust gas collection. Further improvement of the design of electrolyzers should follow the path of increasing its unit capacity, mechanization and automation of all maintenance operations, complete capture of all waste gases with subsequent regeneration of their valuable components.

Industrial electrolysis plants have many types of design, the main ones being membrane and diaphragm. There are also dry, wet and flow electrolysis plants. IN general view installation is closed system, containing electrodes placed in an electrolyte composition, to which an electric current with certain characteristics is supplied. Electrolysis cells can be combined into a battery. There are also bipolar electrolyzers - where each electrode, with the exception of the outer ones, works on one side as an anode, on the other side as a cathode.

This equipment operates at different pressures, depending on the type of reaction. To obtain some substances - for example, when obtaining gases, pressure adjustment or special conditions are required. You also need to monitor the pressure of gases that are a byproduct of electrolytic reactions. Electrolysis plants, which are used to produce hydrogen and oxygen at power plants, operate under excess pressure of up to 10 kgf/cm2 (1 MPa).
The installations also differ in their productivity.

Some of them use linear electric mechanisms. For example, they are used to move electrodes, regulate electrolyte levels, move reservoirs, electrolyte baths, etc. One example of such a design is shown in the drawing.

All electrolysis installations must be grounded. To operate a large industrial electrolyzer, a rectifier unit or a converter substation is needed to convert alternating current into direct current. Stationary local lighting in electrolysis workshops (buildings, halls) is usually not required. Exception - basic industrial premises electrolysis plants for chlorine production.

Industrial electrolysis technologies are divided into several types:

• PFPB - electrolysis technology using baked anodes and point feeders
• CWPB - electrolysis using baked anodes and a center punching beam
• SWPB - peripheral processing of electrolysers with baked anodes
• VSS - Soderberg technology with top current supply
• HSS - Soderberg technology with side current supply

The largest volume of specific emissions from electrolysers comes from electrolysis processes, which are based on Soderberg technology. This technology is most widespread at aluminum smelters in Russia and China. The volume of specific emissions from such electrolyzers is significantly higher compared to other technologies. The amount of fluorocarbon emissions is reduced, among other things, by studying the technological parameters of the anode effect, the reduction of which also affects the amount of emissions.

Models of industrial electrolysers

Carbon anodes (and graphite is an allotope of carbon) have a significant drawback - during the reaction, they emit carbon dioxide into the atmosphere, thereby polluting it. Currently, inert anode technology is especially relevant; this technology is currently being tested famous manufacturer aluminum Its essence is that a non-reactive carbon-free anode is used, and not carbon dioxide, but pure oxygen is released into the atmosphere as a by-product.

This technology significantly increases the environmental friendliness of production, but it is still at the testing stage.

Despite big variety electrolytes, electrodes, electrolysers, available common problems technical electrolysis. These include the transfer of charges, heat, mass, and the distribution of electric fields. To speed up the transfer process, it is advisable to increase the speed of all flows and use forced convection. Electrode processes can be controlled by measuring limiting currents.

Electrolysis is widely used in the industrial sector, for example, to produce aluminum (apparatuses with baked anodes PA-300, PA-400, PA-550, etc.) or chlorine (Industrial units Asahi Kasei). In everyday life, this electrochemical process was used much less frequently; examples include the Intellichlor pool electrolyzer or plasma welding machine Star 7000. Increasing fuel costs, gas and heating tariffs have radically changed the situation, making the idea of ​​electrolysis of water at home popular. Let's consider what devices for splitting water (electrolyzers) are, and what their design is, as well as how to make a simple device with your own hands.

What is an electrolyzer, its characteristics and application

This is the name of the device for the electrochemical process of the same name, which requires external source nutrition. Structurally, this device is a bath filled with electrolyte, in which two or more electrodes are placed.

Main characteristics similar devices– productivity, often this parameter is indicated in the name of the model, for example, in stationary electrolysis plants SEU-10, SEU-20, SEU-40, MBE-125 (membrane block electrolyzers), etc. In these cases, the numbers indicate hydrogen production (m 3 /h).

As for the remaining characteristics, they depend on the specific type of device and scope of application, for example, when electrolysis of water is carried out, the efficiency of the installation is affected by the following parameters:

Thus, by applying 14 volts to the outputs, we will get 2 volts on each cell, while the plates on each side will have different potentials. Electrolyzers that use a similar plate connection system are called dry electrolyzers.

1. The distance between the plates (between the cathode and anode space), the smaller it is, the lower the resistance will be and, therefore, more current will pass through the electrolyte solution, which will lead to increased gas production.
2. The dimensions of the plate (meaning the area of ​​the electrodes) are directly proportional to the current flowing through the electrolyte, and therefore also affect performance.
3. Electrolyte concentration and its thermal balance.
4. Characteristics of the material used to make electrodes (gold is an ideal material, but too expensive, so homemade schemes stainless steel is used).
5. Application of process catalysts, etc.

As mentioned above, settings of this type can be used as a hydrogen generator to produce chlorine, aluminum or other substances. They are also used as devices that purify and disinfect water (UPEV, VGE), and also carry out comparative analysis its quality (Tesp 001).

We are primarily interested in devices that produce Brown's gas (hydrogen with oxygen), since it is this mixture that has every prospect for use as an alternative energy carrier or fuel additives. We will look at them a little later, but for now let’s move on to the design and operating principle of a simple electrolyzer that splits water into hydrogen and oxygen.

Device and detailed operating principle

Devices for the production of detonating gas, for safety reasons, do not involve its accumulation, that is, the gas mixture is burned immediately after production. This simplifies the design somewhat. In the previous section, we examined the main criteria that affect the performance of the device and impose certain performance requirements.

The principle of operation of the device is shown in Figure 4; a constant voltage source is connected to electrodes immersed in an electrolyte solution. As a result, a current begins to pass through it, the voltage of which is higher than the decomposition point of water molecules.

As a result of this electrochemical process, the cathode releases hydrogen, and the anode releases oxygen, in a ratio of 2 to 1.

Types of electrolyzers

Let's take a quick look at design features main types of water splitting devices.

Dry

The design of a device of this type was shown in Figure 2; its peculiarity is that by manipulating the number of cells, it is possible to power the device from a source with a voltage significantly exceeding the minimum electrode potential.

Flow-through

A simplified design of devices of this type can be found in Figure 5. As you can see, the design includes a bath with electrodes “A”, completely filled with solution and a tank “D”.

The operating principle of the device is as follows:

• at the entrance of the electrochemical process, the gas together with the electrolyte is squeezed into container “D” through pipe “B”;
• in tank “D” gas is separated from the electrolyte solution, which is discharged through the outlet valve “C”;
• the electrolyte returns to the hydrolysis bath through pipe “E”.

Membrane

The main feature of devices of this type is the use of a solid electrolyte (membrane) on a polymer basis. The design of devices of this type can be found in Figure 6.

The main feature of such devices is the dual purpose of the membrane: it not only transfers protons and ions, but also physically separates both the electrodes and the products of the electrochemical process.

Diaphragm

In cases where diffusion of electrolysis products between the electrode chambers is not permissible, a porous diaphragm is used (which gives such devices their name). The material for it can be ceramics, asbestos or glass. In some cases, polymer fibers or glass wool can be used to create such a diaphragm. Figure 7 shows simplest option diaphragm device for electrochemical processes.

Explanation:

1. Oxygen outlet.
2. U-shaped flask.
3. Hydrogen outlet.
4. Anode.
5. Cathode.
6. Diaphragm.

Alkaline

The electrochemical process is impossible in distilled water; a concentrated alkali solution is used as a catalyst (the use of salt is undesirable, since this releases chlorine). Based on this, most electrochemical devices for splitting water can be called alkaline.

On thematic forums it is advised to use sodium hydroxide (NaOH), which, unlike baking soda(NaHCO 3), does not corrode the electrode. Note that the latter has two significant advantages:

1. Iron electrodes can be used.
2. No harmful substances are released.

But one significant drawback negates all the benefits of baking soda as a catalyst. Its concentration in water is no more than 80 grams per liter. This reduces the frost resistance of the electrolyte and its current conductivity. While the first can still be tolerated in the warm season, the second requires an increase in the area of ​​the electrode plates, which in turn increases the size of the structure.

Electrolyzer for hydrogen production: drawings, diagram

Let's look at how you can make a powerful gas burner, powered by a mixture of hydrogen and oxygen. A diagram of such a device can be seen in Figure 8.

Explanation:

1. Burner nozzle.
2. Rubber tubes.
3. Second water seal.
4. The first water seal.
5. Anode.
6. Cathode.
7. Electrodes.
8. Electrolyzer bath.

Figure 9 shows circuit diagram power supply for the electrolyzer of our burner.

For a powerful rectifier we will need the following parts:

• Transistors: VT1 – MP26B; VT2 – P308.
• Thyristors: VS1 – KU202N.
• Diodes: VD1-VD4 – D232; VD5 – D226B; VD6, VD7 – D814B.
• Capacitors: 0.5 µF.
• Variable resistors: R3 -22 kOhm.
• Resistors: R1 – 30 kOhm; R2 – 15 kOhm; R4 – 800 Ohm; R5 – 2.7 kOhm; R6 – 3 kOhm; R7 – 10 kOhm.
• PA1 is an ammeter with a measurement scale of at least 20 A.

Brief instructions on parts for the electrolyzer.

A bathtub can be made from an old battery. The plates should be cut 150x150 mm from roofing iron (sheet thickness 0.5 mm). To work with the power supply described above, you will need to assemble an 81-cell electrolyzer. The drawing for installation is shown in Figure 10.

Note that servicing and managing such a device is not difficult.

DIY electrolyzer for a car

On the Internet you can find many diagrams of HHO systems, which, according to the authors, allow you to save from 30% to 50% of fuel. Such statements are too optimistic and, as a rule, are not supported by any evidence. A simplified diagram of such a system is shown in Figure 11.

In theory, such a device should reduce fuel consumption due to its complete burnout. To do this, Brown's mixture is supplied to the fuel system air filter. This is hydrogen and oxygen obtained from an electrolyzer powered by internal network car, which increases fuel consumption. Vicious circle.

Of course, a PWM current regulator circuit can be used, a more efficient switching power supply can be used, or other tricks can be used to reduce energy consumption. Sometimes on the Internet you come across offers to purchase a low-ampere power supply for an electrolyzer, which is generally nonsense, since the performance of the process directly depends on the current strength.

This is like the Kuznetsov system, the water activator of which is lost, and the patent is missing, etc. In the following videos, where they talk about undeniable advantages such systems, there are practically no reasoned arguments. This does not mean that the idea has no right to exist, but the declared savings are “slightly” exaggerated.

DIY electrolyzer for home heating

Making a homemade electrolyzer for heating a house at the moment does not make sense, since the cost of hydrogen obtained by electrolysis is much more expensive natural gas or other coolants.

It should also be taken into account that no metal can withstand the combustion temperature of hydrogen. True, there is a solution, patented by Stan Martin, that allows you to circumvent this problem. There is a key point to pay attention to that allows you to distinguish a worthy idea from obvious nonsense. The difference between them is that the first is issued a patent, and the second finds its supporters on the Internet.

This could be the end of the article about household and industrial electrolysers, but it makes sense to make a short overview of the companies producing these devices.

Overview of electrolyzer manufacturers

Let's list the manufacturers that produce fuel cells based on electrolysers; some companies also produce household devices: NEL Hydrogen (Norway, on the market since 1927), Hydrogenics (Belgium), Teledyne Inc (USA), Uralkhimmash (Russia), RusAl (Russia, significantly improved Soderberg's technology), RutTech (Russia).