Electrolysis installations. Industrial hydrogen generators

The essence of the electrolysis technological process (Fig.) is that when electric direct current flows through the electrolytic bath, one of the following phenomena can occur:

Either particles of the substance are deposited from the electrolyte on the electrodes of the bath (electroextraction)

Or there is a transfer of substance from one electrode to another through the electrolyte (electrolytic refining)

BOOKMARK

Solutions of salts, acids and bases, usually in water, are used as electrolytes.

Ionic conductivity occurs in the electrolyte. When voltage is applied to the electrodes, ions move towards the electrodes, are neutralized and settle on them. In this case, either electroextraction or electrolytic refining takes place.

The concept of normal potential is of primary importance when choosing.

If the electrode is made of the same metal as the electrolyte, then at a certain potential there is neither the first nor the second process between the electrode and the electrolyte. This potential is called normal.

If a more negative potential is applied to the electrodes, electrical extraction begins.

If more positive, then electrolytic refining.

Electrolysis is used to obtain or purify metals.

Quantitatively, the electrolysis process is described by the same Faraday law.

U el =E r +E p +U e +U s

E r - decomposition voltage

E p – sum of anodic and cathodic PN

U e – voltage drop across the electrolyte

U с – voltage drop on the electrode contact buses

U e =I∙R in

U e =I∙(R w +R k +R e)

P el =I∙(E p +E p +U e +U s)

τ – technological process time

E p – useful work

The efficiency of the electrolysis process is described by the mass of the substance.

The raw material for obtaining Zn is zinc blende ZnS. This mineral is first oxidized, roasted, and then leached.

ZnSO 4 +H 2 O(5÷6%) The conductivity of such a solution is low, so add 10÷12% H 2 SO 4 to this solution

The electrolytic bath is made of wood or concrete and is insulated from the ground.

The electrolysis process is carried out at t= 35÷40 0 C

j= 400÷600 A/m 2

PN appears at the cathode - 1.1 V (normal potential -0.76 V)

Electroextraction occurs - the deposition of Zn on the cathode.

1/g e = 3500 kW∙h/t

τ = 40÷50 hours

After this, Zn is stripped from the cathode and melted.

ReceiptAl

The electrolyte is not a solution, but a melt. Alumina Al 2 O 3 is used as raw material

tpl = 2050 0 C

The melt of this material has low conductivity. Therefore, alumina and Na 3 AlF 6 cryolite are used as electrolytes

t pl = 950 0 C

Baths and electrodes are made of coal or graphite.

I= 200÷250 kA

j= 7÷10 kA/m 2

1/g e = 14000÷16000 kW∙h/t

Electroplating

This is an electrotechnological process of deposition of metal onto the surface of both metal and non-metal products using electrolysis.

The thickness of the coating does not exceed tens of microns.

There are 2 varieties:

electroplating

electrotype

Electroplating – copper plating, gilding, gold plating, chrome plating, nickel plating…

Before treatment, the surface is thoroughly cleaned, then etched with acid H 2 SO 4, HCl. A solution of a salt of the applied metal is used as an electrolyte. Sometimes acids and alkalis are added to increase conductivity. The anode is made of the deposited metal, the product is the cathode.

The metal is transferred from the anode to the cathode, processing occurs at low current densities, no more than tens of A/m 2.

Galvanoplasty – obtaining exact copies of products.

Electrodynamic effect and electric wind

When EF acts on gaseous and liquid media, their movement is observed. It is caused by the transfer of kinetic energy during the collision of ions of the medium with neutral molecules.

This phenomenon is called electric wind for gaseous media.

The electric wind is always directed away from the electrode with a smaller radius of curvature.

The force of influence on an electric discharge is assessed simply:

F=E∙ρρ– charge density

Some patterns of electric wind have been established:

Pulse installations

1. Installations for electrical discharge machining.

2.Electro-hydraulic processing installations.

3. Electric pulse welding installations.

4. Installations for magnetic pulse processing of metal.

5. Installations for pulsed electrochemical processing.

1. Installation of electrical discharge machining.

The operation of these devices is based on the phenomenon of electrical erosion, i.e. the destruction of the material being processed (Me) under the action of current pulses flowing between the electrode and the surface being processed, usually in a dielectric medium.

When current pulses flow in the spark channel, electricity is converted into heat in the spark channel between the electrodes and the surface. Heating occurs and is removed.

Main processing parameters:

Pulse repetition frequency from hundreds to hundreds of thousands of Hz,

Current amplitude from fractions to thousands of A,

The pulse duration ranges from fractions to several thousand seconds.

By changing these parameters, the required processing mode is set. Scheme 1.

1-vertical machine stand

2-working bath

3-table for installing a working bath, which ensures movement of the working bath along two coordinates in the horizontal plane.

A 4-reversible electrode product located inside the working bath and moving with it.

5-device for vertical movement.

6-source of high pulse voltage (periodic, not lower than 1 kV).

7-system for supplying working dielectric fluid (usually transformer oil). The system includes pumps, filters, liquid return systems, and coolers.

8-electrode-tool, made of a more refractory material than the electrode-product (tungsten, graphite).

Installation operation

The electrode-tool (8) is brought to the surface of the product (4) and the voltage source (6) is turned on.

Those. High voltage pulses are applied to the gap between the electrode-tool (8) and the product (4) and electric spark discharges occur in this gap. These channels are very concentrated transducers electrical energy into thermal with a bulk density of 10^12 J/m3.

In this case, the power density is 1-10^7 W/cm2. Stand out thermal energy leads to heating, melting, evaporation of the metal of the product and its removal using a working fluid. In this case, multiple electrical discharges pass layer by layer throughout the entire surface being treated. As a result, depressions are formed in the product that copy the shape of the electrode.

Switching power supplies based on capacitive energy storage devices are used as power sources.

Scheme 2.

Power comes from a 220V network using a current transformer. The increased voltage is rectified using a rectifier VD, the rectified voltage is used to periodically load the capacitor bank Cb. After charging this capacitance, a discharge circuit is formed containing inductance Lp and a working spark gap. The capacitance is discharged, and current Lp flows in the discharge circuit. After this, the thyristor VD is turned off and the process of charging the capacitance Sb is repeated. The processing mode (roughness, productivity) is controlled by changing the power and repetition rate of current pulses.

Such installations have high productivity and high quality processing. For some types of processing, such installations are indispensable.

Disadvantage: wear of the electrode-tool is observed.

Electrohydraulic treatment plants

Such installations are based on the use of electro-hydraulic effect.

The electrohydraulic effect consists of converting electricity stored in a capacitive storage device into mechanical energy of a shock wave using a powerful spark discharge, which is created in a liquid medium (usually water).

Electrical diagram almost the same as in the previous case. The difference is in the length of the discharge gap (it is longer).

Process parameters:

1)
- slope of the rising current;

2) up to 250 kA;

3) up to 100 MW;

4) before
J.

With such parameters, the spark channel has the character of an explosion.

Channel temperature
TO; Pressure
MPa.

Pressure is transferred to the fluid.

Areas of use:

a) knocking out molding rods in castings of complex shapes;

b) cleaning castings and various surfaces from scale;

c) crushing, grinding of various materials;

d) recycling of reinforced concrete products.

Pulse welding units

Designed to produce one-piece welded metal connections by compressing the junction and heating it to the melting temperature by passing a pulsed current.

The process diagram is the same as in the previous case. The only difference is the load. The parts hardly heat up.

The advantage is the localization of thermal effects, eliminating the destruction of small welded parts.

Magnetic pulse processing devices

These installations are based on the conversion of EE into the energy of a pulsed MF, then the interaction of the pulsed fields created by the tool - the inductor - with the elec- tric induced by it occurs. Electric shock in the workpiece.

As a result, the MF energy is converted into mechanical energy, which deforms the workpiece in the necessary manner.

Charger – charger;

- battery of inductors (creates a pulse of the desired shape);

IN – inductor tool;

Z – workpiece.

Multi-circuit and single-circuit installations

Multi-circuit installation contains one or more tools - inductors, made in the form of solenoids.

Solenoid MF generated by current induces current in the workpiece . The currents interact and provide mechanical forces and deformation of the workpiece.

- AI’s own inductance;

- active resistance to AI;

- active resistance ;

- coefficient of mutual induction;

- inductance and active resistance of the workpiece.

In the scheme prot. PP, it is determined by the TOE method. The technology of operation according to this scheme is used in 3 variants:

2) distribution (induction inside the workpiece);

3) sheet molding (the flat workpiece is deformed).

Single-circuit circuit:

In this case, the discharge current flows directly through the workpiece. Procurement is part of AI.

branches into And . The interaction of currents leads to deformation of the workpiece, and it takes on the shape shown in the dotted line.

Advantages:

Flaws:

The material must have high electrical conductivity;

The need to install conductive gaskets when formation of materials, poorly conductive electrical current;

Difficulties surface treatments, having a gap for el. current;

Difficulties in processing massive workpieces.

Installations for pulsed electrochemical processing. These are the electrochemical technological processes discussed above, in which pulsed voltage is used instead of constant voltage.

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, membrane installation SEU-40 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 expensive, but ideal material for use in electrolysers. 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 come in 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 operating principle is configured in some welding machines– the combustion of the released gas allows the elements to be welded.

Membrane type

A membrane-type electrolysis plant has a similar design to other electrolyzers, however, a solid substance acts as an electrolyte. 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;
• small filter running water filter, 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 ensure that 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. By increasing the electric current and 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 principle of operation 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

The First Engineer company offers equipment for the production of hydrogen by electrolysis of water in an alkaline solution (30% potassium hydroxide) - electrolysis plants (industrial hydrogen generators).

Electrolysis is the simplest and affordable way obtaining hydrogen from existing ones.

Advantages of hydrogen production by electrolysis:

• environmental cleanliness;
• wide range of plant performance (1÷500 Nm 3 /h and more);
• high purity of produced hydrogen (up to 99.9999%);
• availability of valuable by-product– oxygen.

Electrolysis is the most common and effective industrial method for producing hydrogen. This method allows the production of hydrogen from useful use of consumed electrical energy is approximately 70%.

The electrolysis process takes place inside galvanic cell(chamber), divided into positive and negative sides, where electric current flows between metal electrodes through a conductive liquid electrolyte (an aqueous solution of alkali). The positive electrode is called the anode, and the negative electrode is called the cathode.

Simple galvanic cell

The cell halves are separated by a wetted membrane, which allows electrical current to flow (via the electrolyte) but prevents the transfer of released gases from one side to the other.

When voltage is applied direct current, current flows through the liquid in contact with the electrodes, resulting in the release of gases:

• reaction at the cathode: 2OH – → 0.5O2 + H2O + 2e –
• reaction at the anode: 2H 2 O + 2e – → H 2 + 2OH –
• total reaction: H 2 O → H 2 + 0.5 O 2.

Only water is consumed inside the galvanic cell. Electrolyte is added to minimize electrical resistance and to promote the reaction by providing an excess of hydroxyl ions (see reaction above) but not consumed in the process.

The amount of gas released at each electrode is directly related to the amount of direct current flowing through the element. A special feature of the alkaline electrolysis process is the ability to operate within a wide load range (starting from 10% of the rated power). Energy consumption for alkaline electrolysis is 4.5÷5.5 kW per 1 Nm 3 of hydrogen produced.

Advantages of electrolysis installations of the First Engineer company:

• possibility of manufacturing standalone installation for gas production (in container version);
• equipment configuration in accordance with client requirements;
• full project support, including interaction with government regulatory authorities (if necessary);
• delivery of units in full factory readiness with passing initial tests at the manufacturer;
• complete automation of equipment operation and no need for constant monitoring by maintenance personnel.

Production time

ELECTROSPETS

ELECTROSPETS

Electrochemical and electrophysical installations, electrolysis installations

Electrolysis- this is the phenomenon of the release of a substance on the electrodes when current passes through the electrolyte, the processes of oxidation and reduction on the electrodes, accompanied by the acquisition or loss of electrons by particles of the substance.
Electrolyzer- this is a bath in which the process occurs with the absorption of electrical energy.
The principle of operation can be seen in the diagram of an electrolyzer with anodic dissolution and cathodic deposition (Fig. 1.3-1).

The main elements of the installation are: electrolyte (1), electrodes (2) and power source (3).
The voltage across the electrolysis bath (U) consists of three components:

A double electrical layer is formed near the surface of the electrodes, which counteracts the approach and exit of ions. To weaken the counteraction, the following are used:
- electrolyte circulation to equalize the temperature;
- vibration of electrodes;
- switching power supply.
In industry, the electrolysis of metals and the initial environment are determined by the electrical potential of the released metal.
Metals with a positive potential are isolated from the solid raw material by dissolving it (for example, copper with a potential of “+0.34 V”).
Metals with a negative potential are released more from solutions of their salts (for example, zinc with a potential of “-0.76 V”).
Metals with a negative potential release less from the melts of their salts (for example, aluminum with a potential of “-1.43”).
Note - Metal potentials are defined in relation to “hydrogen”, which has an electrical potential of “zero”.
Electrolysis of copper used to obtain pure electrolytic copper from rough copper (obtained after smelting in furnaces) and to extract valuable metals contained in it.
The process is carried out in electrolysis baths.
The anode is cast blister copper in the form of plates 35...45 mm thick and weighing about 300 kg.
The cathode is electrolytic (pure) copper in the form of plates 0.6...0.7 mm thick, suspended on ears between the anodes. The distance between adjacent anodes and cathodes is 35...40 mm.
The electrolyte with which the bath is filled is an aqueous solution of copper sulfate (CuSO 4), acidified with sulfuric acid (H 2 S0 4) to reduce resistance.

In order to equalize the concentration of copper ions at the electrodes and ensure the required temperature, direct circulation of the electrolyte is used, which is supplied from below and drained from the top of the bath.
Electrolysis of zinc used to obtain high-quality zinc (Zn) from aqueous solutions of its salts.
The cathode is aluminum plates 4 mm thick. The anode is lead plates 5...8 mm thick, with the addition of 1% silver to reduce corrosion.
The electrolyte is a 5...6% aqueous solution of zinc sulfate (ZnS0 4) and sulfuric acid (H 2 S0 4). During electrolysis, metallic zinc (Zn) is deposited on the cathode, which is periodically removed.
Hydrogen gas (H) is released at the anode, and sulfuric acid (H 2 S0 4) is formed in the solution.

Zinc is removed from cathodes up to 2 times a day, then it is washed, formed into bags and melted in furnaces.
During the electrolysis process, the wear of cathodes is about 1.5 kg/t of zinc, and of anodes - 0.8... 1.5 kg/t of zinc.
A sharp increase in the voltage drop across the bath (up to 3.3...3.6 V) indicates the need to clean the anodes from sludge.
The need to clean anodes is once every 20...25 days, and cathodes - once every 10 days.
The sludge is removed through a hole in the bottom of the bath.
In the electrolysis shop, baths are installed side by side with long sides of 20...30 pieces and connected into one block.
To maintain the set temperature, the baths are cooled with water supplied through aluminum or carbon coils.
To reduce the evolution of hydrogen at the cathode, surfactants are added to the solution.
Aluminum electrolysis used to produce high-quality aluminum (Al) from molten salts by electrolysis.
The anode is a carbon electrode, which is consumed during the electrolysis process, as it is located in a highly aggressive environment.
The anode is suspended on a movable frame, which automatically moves along the metal structures of the furnace. The control signal is the loss of voltage in the electrolyte.
The electrolyte is a solution of aluminum oxide (AI 2 O 3) in molten cryolite (Na 3 AlF 6). The presence of fluorine (F 6) makes the environment highly aggressive.
The cathode is the hearth blocks of the furnace.
Current is supplied to the bath from both sides.
To the anode - via packages of aluminum busbars, via flexible copper conductors, via steel pins.
To the cathode - via special conductors (blooms).
The dimensions of the anode are determined by the specified power of the bath and the permissible current density.

Electrolyzers are combined into a series of 160...170 units, with 4...5 of them being reserve.
Pouring metal from the bath using vacuum ladles
Aluminum poured from the baths enters the mixers of the casting body, where, after averaging and settling, it is poured into ingots.

The electrical equipment of metal-cutting machines is diverse, complex and high level automation. The most widespread type metal cutting equipment There is a relatively small number of types of machines for general industrial use, ubiquitous in enterprises of various profiles. These include universal machines Widely used for turning, drilling, threading, etc.

The electrical equipment of such machines is usually of the same type and is determined by the use of simple electric drives of limited power. In control systems, serial electrical equipment (magnetic and thyristor starters, circuit breakers, various relays, etc.).

As an example, let's look at the main parts and electrical circuit of the 1K62 universal screw-cutting lathe (Fig. 143).

Rice. 143. General form(a) and control diagram (b) of a 1K62 screw-cutting lathe:
1 - front headstock; 2 - spindle; 3 - caliper; 4 - tailstock; 5 - control panel; 6 - lead screw; 7 - shaft; 8 - feed box; 9 - bed

The spindle 2, lead screw 6 and shaft 7 are driven through the gearbox located in the headstock 1 and the feedbox 8 from the main electric motor M 1, hidden inside the frame 9. The power Ml is 10 kW. In addition to the main engine, the machine is equipped with an M4 electric motor (high-speed electric motor for caliper installation movements 3), an M2 cooling pump electric motor and an M3 hydraulic system drive electric motor, connected using the ШР plug connector. The M3 engine is used when a hydrocopier is used on the machine. Tailstock 4 of the machine is used to install a second supporting center (when processing in centers) or cutting tool for processing holes (drill, tap, reamer). The cutters are installed in the head of the caliper, which provides them with longitudinal and transverse feed.

Voltage is supplied to the machine by turning on the batch switch Q1. The control circuit is powered through an isolation transformer T with a secondary voltage of 110 V.

The M1 engine is started by the SVP button, pressing which turns on the KM contactor. Simultaneously with Ml, the M2 engine (cooling pump motor) is started with the package switch Q2 and M3 (hydraulic system motor) turned on with the ШР plug connector turned on.

The operation of the Ml engine at idle speed is limited by the time delay of the CT relay. The CT relay coil is turned on by the SO switch, which closes the contacts when the spindle stops. If the pause in operation exceeds 3 - 8 minutes, then the KT relay contact opens and power is not supplied to the KM contactor, and the Ml engine stops, thereby limiting idling operation, reducing electricity losses.

The operation of the M4 engine depends on the movement of the caliper, which presses the SAB switch, closes the circuit of the KMB contactor coil through the contact and turns on the engine. Returning the caliper handle to the middle position turns off the M4 engine.

Transformer T provides machine lighting with a voltage of 36V. Protection against short circuits is provided by fuses F1 - F5, and against overloads by thermal relays KST1, KST2 and KST5. The M4 engine operates for a short time and does not need overload protection.

Electrical equipment for welding installations

Among the wide variety of welding electrical installations, electric arc welding installations have received wide general industrial use.

The simplest are welding installations (posts) for manual arc welding. The basis of the electrical equipment of such a welding station is the welding current source. Special welding transformers, rectifiers and electrical machine converters of alternating current into direct current are used as sources. In addition to the current source, the welding station includes a distribution board, flexible connecting wires and an electrode holder.

Welding transformers by design and electromagnetic circuits They are divided into transformers: with a separate choke, with a combined choke, with moving windings, with a magnetic shunt and with direct current bias. Chokes, magnetic shunts, moving windings or DC bias are used in these transformers to regulate the welding current.

Rice. 144. Welding transformer with moving coils

Transformers with moving windings are most often used, as they are the simplest and most reliable (Fig. 144). The core of such a transformer is of the rod type, laminated. The primary and secondary windings are layered, with a developed cooling surface. Each winding consists of two coils, which can be connected in series or in parallel. On the magnetic circuit 1 there are a fixed primary 4 and a movable secondary 3 windings, which lead screw using the current control handle 2 are moved along the magnetic core, changing the magnetic leakage flux, and therefore the welding current. To increase the power factor, capacitor 5 is used.

Rice. 145. Welding rectifier:
A - appearance; b - electrical diagram.

Welding rectifiers (Fig. 145) are used when welding with direct current, which provides wider technological capabilities than alternating current. Main components The rectifiers are a three-phase transformer consisting of 3 fixed and 2 movable coils with voltage regulation and a block of VB semiconductor valves 1, assembled according to a three-phase bridge circuit. The welding current is changed by handle 5. An electric fan 4 is used to cool the welding unit.

Semi-automatic gas-shielded and submerged arc welding is becoming increasingly widespread. In polyautomatic welding, the supply of welding wire to the welding zone is mechanized. One of the simplest in design and control is the PSh semiautomatic hose machine for submerged arc welding (Fig. 146).

Rice. 146. Electrical diagram of a step-by-step semiautomatic welding machine PSh

The electric drive of the feeding mechanism uses an asynchronous electric motor M with a squirrel-cage rotor. The motor is connected through a gearbox (not shown in the diagram) to the drive roller VR of the welding wire feed mechanism SP. The motor is powered by two single-phase transformers T1 and T2, which reduce the voltage to a safe value (42 V). The engine reverse for the installation strokes of the feed mechanism is carried out using the PR switch. Stepwise adjustment of the wire feed speed is carried out by changing the gear ratio of the mechanism gearbox.

To control the semi-automatic device, a one-button SB station mounted on the burner handle is used. When SB is pressed, the intermediate relay P is activated, which turns on the feed motor M and the power contactor KM. During operation of the semi-automatic machine, the SB button, which does not have a self-locking mechanism, must be pressed. When releasing SB welding transformer turns off. General switch and the devices are not shown in the diagram.

At welding work fulfill a number of conditions for compliance with labor safety and equipment rules safe work. If electric welding work is carried out indoors, they must be well ventilated. The electric welder must work in special clothing (canvas suit, mittens, boots), and use a helmet or mask with protective glasses to protect the eyes and face.

The welding unit and its equipment are inspected and cleaned at least once a month. Repair of welding equipment is carried out in accordance with the schedule approved by the chief power engineer of the enterprise.

During routine repairs of the installation, the insulation resistance of electrical circuits is measured, and after overhaul insulation is tested for electrical strength.

Electrolysis plants

Electrolysis is an electrochemical process of oxidation-reduction on electrodes immersed in an electrolyte when passing through it electric current. Electrolysis is carried out in special electrolyzer devices.

Electrolyzer is a vessel or system of vessels filled with an electrolyte with electrodes placed in it - a cathode and an anode - connected, respectively, to the negative and positive poles of a direct current source. The process of electrochemical oxidation occurs at the anode, and reduction occurs at the cathode. Anodes are made from graphite, carbon-graphite material, oxides of some metals, lead and its alloys, and cathodes are made from steel.

Modern large electrolysis plants have loads of up to 500 kA. In industry, simple and complex substances are produced using electrochemical processes in electrolysis plants. Electrolysis is the main method for the industrial production of aluminum, caustic soda, chlorine, etc. By electrolysis of water, oxygen and hydrogen are obtained. Electrolysis is also used for surface treatment by electroplating (cathode processes), polishing, etching, and anodizing (anodic processes) of metal products.

Metal coating is carried out in galvanic baths at a voltage of 3.5 - 24 V and currents up to 500 A. The power supply of the baths is carried out from the common lines of the converters, and the voltage and current are regulated using rheostats. If several baths are powered from one generator, then they are turned on in parallel with the installation of a rheostat at each bath. The busbar is made, as a rule, from aluminum busbars with welded contact connections that have lower transition resistance than bolted contact connections.

Maintenance of electrolysis installations consists of organizing periodic inspections, measuring the insulation resistance of all parts of the installation and carrying out repairs in accordance with PPREO schedules.

The electrician on duty carries out an external inspection of the installations every shift. During the inspection, attention is paid to the temperature of the contact connections, the condition of the busbars, the absence of short circuits in the anode and cathode circuits, the condition of the insulation surface of the busbars (insulators, gaskets, clasps, etc.), the presence and serviceability of protective devices. In addition, the potential at the ends of the electrolysis bath lines relative to the ground is measured.

The insulation resistance of all parts of the installation is measured at least once every three months.

Overhaul of all conductive elements of electrolysis installations is carried out at least once a year, and for those areas that are in the zone high temperatures or are subject to corrosion, mechanical stress, the frequency can be reduced and is established by local instructions.

Electrothermal installations

Electric furnaces are used to heat, melt or process metals by thermal effect electrical phenomena. Based on the method of converting electrical energy into heat, arc, induction and resistance furnaces are distinguished.

The electric furnace installation includes an electric furnace, an electric furnace transformer, a rectifier, a high-frequency generator; switching equipment (switch, disconnector, etc.) and auxiliary equipment(chokes, capacitors, anode rectifiers, etc.). Electric ovens are energy-intensive units.

Electric arc furnaces are used for melting steel, cast iron, copper and other metals. The power of these furnaces reaches 80,000 kW. The section of the electrical network from the transformer to the furnace electrodes consists of busbars, flexible connections and conductors. In this network, the current reaches several tens of thousands of amperes.

Single-phase induction furnaces (Fig. 147) operate at various current frequencies (50-75,000 Hz). Heating occurs due to currents induced in the metal.

Rice. 147. Induction heating installation diagram:
1 - power supply; 2 - capacitor; 3 - inductor; 4 - heated body; 5 - crucible.

Normal frequency induction furnaces are a transformer in which the role of the secondary winding is played by a metal bath in the form of a closed ring. The power of these furnaces reaches 17,000 kW.

Induction heating installations are widely used for drying electrical machines, apparatus, heating liquids in pipelines, etc. Furnaces operating at a frequency of 2500 - 8000 Hz are used for hardening metals.

Electrical inspection furnace installations produced daily. During inspections, dust and dirt are removed, the condition of contacts of electrode holders, busbars, cables, wires, and lubrication of mechanisms is checked. Special attention pay attention to the operation and condition of the locking devices: disruption of their operation can lead to disruption of technology, equipment breakdown and accidents. Periodically, in arc furnaces, scale is cleaned from the contact surfaces of electrode holders, and oil samples are taken from transformers of furnace installations for analysis.

When inspecting resistance furnaces, pay attention to the operation of the heating elements. Operation of furnaces with faulty heating elements, with heaters installed on other grades of alloy; disabled elements; uneven load across phases on furnaces with ceramic heaters is not allowed. Each installation electric oven resistance must have maintenance instructions. All operating personnel undergo special training in the operation of these furnaces and compliance with labor safety regulations.

Repairs of electric furnace installations are carried out in accordance with the schedule established by the chief power engineer of the enterprise.

Rechargeable batteries

The main parts of an acid battery are a tank with electrolyte and lead plates, isolated from each other by separators. Lead plates with a large number ribs that increase the working surface, and as negative ones - box-shaped plates. The electrolyte is a mixture of sulfuric acid and distilled water. Chargers and rechargers are used to replenish electrical energy in batteries.

As a rule, rechargeable batteries are operated in constant recharge mode. In this case, the charged battery is connected to the buses in parallel with a constantly running charger. The constant recharging method increases the reliability of the electrical installation and provides a reserve in case of failure charger. The battery is kept in a fully charged state. The voltage level on each element should be 2.1 -2.2 V. The electrolyte density is maintained at 1.24.

Alkaline batteries are divided into cadmium-nickel and iron-nickel. The tanks are made of nickel-plated iron. The electrolyte is prepared in a steel or enamel container and replaced annually. To do this, the batteries are discharged to a voltage of 1 V, the electrolyte is drained, washed with distilled water and immediately filled with fresh electrolyte. After 2 hours, check the density of the electrolyte and bring it to normal (at t = 20 ° C it should be equal to 1.19-1.21) and turn it on for charging. At the beginning of charging, the battery voltage rises sharply from 1 V to 1.6 V, then slowly increases to 1.75 V. The end of charging is a steady voltage for 20 - 30 minutes (for iron-nickel - 1.8-1.9 V and for cadmium-nickel 1.75-1.85 V).

When servicing battery installations, the operating rules are strictly followed to ensure proper and trouble-free operation and safe maintenance. In room batteries maintain cleanliness and monitor work supply and exhaust ventilation. Ventilation should be turned on during the entire battery charging period and for 1.5 - 2 hours after charging.

In these premises it is prohibited to install fuses, sockets, circuit breakers, fluorescent lamps, switches that may cause a spark.

Inspection of batteries is carried out at the following times: electrician on duty - daily, foreman - twice a month, battery specialist - according to schedule.

All metal parts in the battery room are painted with acid-resistant paint. Painted and unpainted battery tires are lubricated with Vaseline.

When working with acid or alkali, be sure to wear a suit made of coarse wool, safety glasses, rubber gloves, and tuck the suit trousers over the tops rubber boots. Carrying bottles with acid or alkali requires two people on a special stretcher in which the bottle is secured. When preparing the solution, the acid should be poured in a thin stream into a vessel with distilled water (and not vice versa!). Areas of skin affected by acid are washed with a jet cold water and neutralize with a 5% soda solution, and in case of a burn with alkali, wash with a stream of water and neutralize with a solution of boric acid.