The electrical equipment of metal-cutting machines is diverse, complex and has a high level of automation. The most widespread type of metal-cutting equipment is a relatively small number of types of machine tools for general industrial purposes, ubiquitous in enterprises of various profiles. These include universal machines general purpose 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 is widely used (magnetic and thyristor starters, circuit breakers, various relays, etc.).

As an example, consider the main parts and the electrical circuit of the 1K62 universal screw-cutting lathe (Fig. 143).

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

The drive of the spindle 2, the lead screw 6 and the shaft 7 is carried out through the gearbox located in the headstock 1 and the feed box 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 (an electric motor for high-speed installation movements of the caliper 3), an electric motor for the cooling pump M2 and an electric motor for driving the hydraulic system M3, connected using a ShR plug connector. The M3 engine is used when a hydrocopy device is used on the machine. tailstock 4 machines serves to install a second supporting center (when processing in centers) or cutting tool for processing holes (drills, taps, reamers). The cutters are installed in the head of the caliper, which informs them of the longitudinal and transverse feed.

The machine is energized by turning on the package switch Q1. The control circuit is powered through an isolating transformer T with a secondary voltage of 110 V.

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

The operation of the engine Ml at idle is limited by the time delay of the relay KT. The CT relay winding is switched on by the SO switch, which closes the contacts when the spindle stops. If the pause in operation exceeds 3 - 8 minutes, then the contact of the relay KT opens and the contactor KM is not powered, and the motor Ml stops, thereby limiting the work idle move reducing power losses.

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

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

Electrical equipment of welding installations

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

The simplest are welding installations (posts) for manual arc welding. The basis of the electrical equipment of such a welding station is the source of welding current. As sources, special welding transformers, rectifiers and AC-DC converters are used. In addition to the current source, the welding station includes switchboard, connecting flexible wires and electrode holder.

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

Rice. 144. Welding transformer with moving coils

The most commonly used transformers with movable windings, as the most simple and reliable (Fig. 144). The core of such a transformer is of a 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 fixed primary 4 and movable secondary 3 windings, which lead screw using the current control knob 2, they move along the magnetic circuit, changing the magnetic leakage flux, and, consequently, the welding current. Capacitor 5 is used to improve the power factor.

Rice. 145. Welding rectifier:
a - appearance; b - electrical circuit.

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

Semi-automatic welding in shielding gases and submerged arc is becoming more and more widespread. In poly-automatic welding, the feed is mechanized welding wire to the welding area. One of the simplest in design and control is the PSH semi-automatic hose for submerged arc welding (Fig. 146).

Rice. 146. The electrical circuit of the semiautomatic step welding semiautomatic device PSh

In the electric drive of the feeder, asynchronous electric motor M with squirrel-cage rotor. The engine through a gearbox (not shown in the diagram) is connected 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 lower the voltage to a safe value (42 V). The engine reverse for the adjustment moves of the feed mechanism is carried out using the PR switch. Stepped adjustment of the wire feed speed is made by changing the gear ratio of the mechanism reducer.

To control the semiautomatic device, a one-button SB post 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 the operation of the semiautomatic device, the SB button, which does not have self-locking, must be pressed. When you release SB welding transformer turns off. The general switch and devices are not shown in the diagram.

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

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.

At current repairs installations measure the insulation resistance of electrical circuits, 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 while passing through it electric current. Electrolysis is carried out in special electrolyzers.

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

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

Metal plating is carried out in electroplating baths at a voltage of 3.5 - 24 V and currents up to 500 A. The baths are powered from the common lines of the converters, and the voltage and current are regulated using rheostats. If several baths are fed from one generator, then they are switched on in parallel with the installation of a rheostat at each bath. The busbar is made, as a rule, from aluminum tires with welded contact joints, which have a lower contact resistance than bolted connections contacts.

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

The electrician on duty conducts an external inspection of the installations every shift. During the inspection, attention is drawn to the temperature of the contact joints, the condition of the busbars, the absence of short circuits in the circuit of anodes and cathodes, the condition of the surface of the insulation of the busbars (insulators, gaskets, clamps, etc.), the presence and serviceability of protective devices. In addition, the potential at the ends of the electrolysis cell lines with respect to earth 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 plants is carried out at least once a year, and for those areas that are in the zone high temperatures or subject to corrosion, mechanical stress, the frequency may be reduced and is established by local regulations.

Electrothermal plants

Electric furnaces are used to heat, melt or work metals by thermal effect electrical phenomena. According to the method of transformation electrical energy in thermal, arc, induction and resistance furnaces are distinguished.

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

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 tires, flexible connections and a conductor. 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. Installation diagram induction heating:
1 - power supply; 2 - capacitor; 3 - inductor; 4 - heated body; 5 - crucible.

Induction furnaces of normal frequency are a transformer in which the role of the secondary winding is performed 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.

Inspection of electric furnace installations is carried out daily. During inspections, remove dust, dirt, check the condition of the contacts of the electrode holders, busbars, cables, wires, lubrication of mechanisms. Special attention pay to work and state blocking devices: violation of their work can lead to a violation of technology, equipment breakdown and accidents. Periodically, in arc furnaces, the scale is cleaned from the contact surfaces of the electrode holders, and oil samples are taken from the 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 on phases on furnaces with ceramic heaters is not allowed. Each installation electric oven resistance must have a maintenance manual. Whole service staff passes special education on the operation of these furnaces and compliance with labor protection rules.

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 of ribs are used as positive ones, increasing work surface, and as negative - box-shaped plates. The electrolyte is a mixture of sulfuric acid and distilled water. Charging and recharging devices are used to replenish electric energy in accumulators.

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

Alkaline batteries are divided into cadmium-nickel and iron-nickel. Tanks are made of nickel-plated iron. The electrolyte is made up in a steel or enamel bowl and is 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, the density of the electrolyte is checked and adjusted to normal (at t = 20 ° C, it should be equal to 1.19-1.21) and switched 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 the charge 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 strictly observe the rules of operation to ensure proper and trouble-free operation and its safe maintenance. In room batteries maintain cleanliness and monitor work supply and exhaust ventilation. Ventilation must be turned on during the entire time of battery charging and 1.5 - 2 hours after it ends.

It is forbidden to install fuses in these rooms, socket outlets, vending machines, fluorescent lamps, switches, which may generate a spark.

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

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

When working with acid or alkali, be sure to wear a suit made of coarse wool, goggles, rubber gloves, suit trousers tucked over the tops of rubber boots. It is necessary to carry bottles with acid or alkali together on a special stretcher in which the bottle is fixed. During the preparation of the solution, the acid should be poured in a thin stream into a vessel with distilled water (and not vice versa!). Acid-affected areas of the skin are washed with a stream of cold water and neutralized with a 5% soda solution, and in case of an alkali burn, they are washed with a stream of water and neutralized with a solution of boric acid.

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

Or there is a deposition of particles of a substance from the electrolyte on the electrodes of the bath (electroextraction)

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

BOOKMARK

As an electrolyte, solutions of salts, acids and bases, usually in water, are used.

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

The notion of a normal potential is of primary importance in the choice.

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. Such a potential is called normal.

If a more negative potential is applied to the electrodes, then electroextraction 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 email \u003d E p + E p + U e + U s

E p - decomposition voltage

E p - the sum of the anode and cathode PN

U e - voltage drop on the electrolyte

U s - voltage drop on the electrode contacts buses

U e \u003d I ∙ R ext

U e \u003d I ∙ (R w + R to + R e)

P el \u003d I ∙ (E p + E p + U e + U s)

τ - time technological process

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 subjected to oxidation, roasting, and then subjected to leaching.

ZnSO 4 +H 2 O(5÷6%) The conductivity of such a solution is low, therefore, 10÷12% H 2 SO 4 is added 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 on the cathode - 1.1 V (normal potential -0.76 V)

Electroextraction occurs - deposition of Zn on the cathode.

1/g e = 3500 kWh/t

τ = 40÷50 hours

After that, Zn is stripped from the cathode and remelted.

ReceiptAl

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

t pl \u003d 2050 0 С

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

t pl \u003d 950 0 С

Bathtubs and electrodes are made of carbon 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 metal deposition on the surface of both metal and non-metal products using electrolysis.

The coating thickness does not exceed tens of microns.

There are 2 varieties:

electroplating

electrotype

Electroplating - copper plating, gilding, gilding, chromium plating, nickel plating ...

Before processing, the surface is thoroughly cleaned, then acid etching is carried out with H 2 SO 4 , HCl. The salt solution of the deposited metal is used as the electrolyte. Sometimes acids and bases are added to increase conductivity. The anode is made of deposited metal, the product is the cathode.

There is a transfer of metal from the anode to the cathode, processing occurs at low current densities, not more than tens of A/m 2 .

Galvanoplasty - obtaining exact copies from products.

Electrodynamic effect and electric wind

Under the action of an EF on gas and liquid media, their movement is observed. It is due to the transfer of kinetic energy during the collision of ions of the medium with neutral molecules.

This phenomenon is called the electric wind for gaseous media.

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

The strength of the impact on the electric discharge is estimated simply:

F=E∙ρρ– charge density

Some regularities of the electric wind have been established:

Impulse installations

1. Installations of electroerosive processing.

2. Installations of electro-hydraulic processing.

3. Electric pulse welding installations.

4. Installations for magnetic pulse metal processing.

5. Installations of pulsed electrochemical processing.

1. Installation for electroerosive processing.

The operation of these devices is based on the phenomenon of electroerosion, that is, the destruction of the material being processed (Me) under the action of current pulses flowing between the electrode of 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. There is heating, and its removal.

Main processing parameters:

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

Current amplitude from fractions to thousands of A,

The duration of impulses is 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 the installation of the working bath, which ensures the movement of the working bath in two coordinates in the horizontal plane.

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

5-device for vertical movement.

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

7-system for supplying the working dielectric liquid (usually transformer oil). The system includes pumps, filters, liquid return systems, 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), the product (4), and electric spark discharges occur in this gap. These channels are very concentrated converters of electrical energy into thermal energy 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 with the help of a working fluid. In this case, multiple electrical discharges pass layer by layer throughout the entire surface to be treated. As a result, recesses are formed in the product, which 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 the VD rectifier, the rectified voltage is used to periodically load the capacitor bank Cb. After charging this capacitance, a discharge circuit is formed containing the inductance Lp and the working spark gap. The capacitance is discharged, a current Lp flows in the discharge circuit. After that, the thyristor VD is closed and the process of charging the capacitance Sat is repeated. The processing mode (roughness, productivity) is controlled by changing the power and frequency of the current pulses ip.

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

Disadvantage: there is wear of the tool electrode.

Electro-hydraulic treatment plants

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

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

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

Technological process parameters:

1)
- steepness 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.

The pressure is transferred to the fluid.

Areas of use:

a) knockout of molding cores in castings complex shape;

b) cleaning of castings and various surfaces from scale;

c) crushing, grinding of various materials;

d) recycling of reinforced concrete products.

Pulse welding plants

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

The scheme of the process is the same as in the previous case. The difference is only in the load. Parts don't get hot at all.

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

Magnetic pulse processing devices

These installations are based on the conversion of EE into the energy of a pulsed MF, then there is an interaction of the pulsed fields created by the tool - the inductor, with the El induced by it. current in the workpiece.

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

ZU - charger;

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

IN - tool inductor;

Z - blank.

Multi-circuit and single-circuit installations

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

MP of the solenoid created by the current induces current in the workpiece . The currents interact and provide mechanical forces and deformation of the workpiece.

- intrinsic inductance of AI;

- AI active resistance;

- active resistance ;

- coefficient of mutual induction;

- inductance and active resistance of the workpiece.

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

2) distribution (induction inside the workpiece);

3) sheet forming (a flat billet is deformed).

Single circuit diagram:

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

branches into and . The interaction of currents leads to deformation of the workpiece, and it acquires the shape shown by the dotted line.

Advantages:

Flaws:

The material must have high electrical conductivity;

The need to install conductive gaskets when forming materials that do not conduct electricity well. current;

Difficulties in processing surfaces that have a gap for el. current;

Difficulties with processing massive workpieces.

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

Electrolysis is the phenomenon of the release of a substance on the electrodes when a current passes through the electrolyte, the processes of oxidation and reduction on the electrodes, accompanied by the acquisition or loss of electrons by the particles of the substance.

An electrolyser is a bath in which the process proceeds with the absorption of electrical energy.

Operating principle:

Rice. 1.1.

The main elements of the installation are: electrolyte 1, electrodes 2 and power supply 3.

The electrolysis cell voltage (U) consists of three components:

U = U1 + Uak + Ue, (1.1)

Uac - near-electrode voltage;

Ue is the voltage in the electrolyte.

The power released in the electrolysis bath (Rev) is determined by the expression:

Rev = I(U1 + Uа + Uк + Il/σ), (1.2)

where I is the current in the bath, A;

Uа, Uк – voltage drop across the anode and cathode, V;

l is the distance between the electrodes, m;

σ is the specific conductivity of the electrolyte, 1/(Ohm m).

Only part of this power is spent on the decomposition of matter. The rest of the power goes to heating the electrolyte and transporting ions through the solution. The efficiency of the electrolysis process is estimated by the energy output (Ae, %).

Аe=α·(Ат/U)·10 2 , (1.3)

where α is the electrochemical equivalent of a substance;

Am is the current output of the metal, g/J;

U is the voltage on the electrolyzer, V.

The current output of a metal is the amount of metal (g) released per unit of energy expended (J).

The intensity of the process is determined by the electrode current density

je = I/S, (1.4)

where I is current, A;

S is the area of ​​the part of the electrode immersed in the electrolyte, m2.

A double electrical layer is formed near the surface of the electrodes, which counteracts the entry and exit of ions. To weaken the resistance, apply:

Electrolyte circulation, for temperature equalization;

Vibration of electrodes;

Switching power supply.

Electrolysis is one of the types of technological processes. Its essence lies in the separation of particles of matter from the electrolyte when a direct current flows through it and in their deposition on electrodes immersed in the electrolyte (electroextraction) or the transfer of matter from one electrode through the electrolyte to another (electrolytic refining).

Electrolysis is applied:

In non-ferrous metallurgy for the production of light metals (aluminum, magnesium, cadmium, etc.) and the refining of heavy metals (copper, silver, gold, nickel, lead, etc.);

In electrochemistry for the production of chlorine, hydrogen, heavy water,

oxygen, fluorine, potassium, sodium, etc.;

In mechanical engineering for applying protective and decorative coatings of metal and non-metal products (zinc plating, nickel plating, cadmium plating, lead plating, copper plating, chromium plating, silver plating, oxidation, etc.);

In ferrous metallurgy for tin plating and electrolytic cleaning.

In metallurgy, two types of electrolysis are used: the electrolysis of aqueous solutions and the electrolysis of molten salts. The first one is used for the production and electrolytic refining of metals with a low normal potential (zinc, chromium, tin, nickel, lead, silver) and is carried out at a temperature not exceeding 100 С, the second one is used to obtain metals with a high normal potential (magnesium, aluminum, alkaline earth metals). metals) at a temperature of about 1000 C.

Electrolysis is carried out in specially equipped baths - electrolyzers. The voltage on the bath is several volts, and the currents reach tens and hundreds of thousands of amperes. In order to economically drain high currents, identical baths are connected in series in series, according to the voltage of the converter installation.

Change electrical resistance baths due to heating of the electrolyte, changes in its chemical composition, current leakage, violations of the normal operation mode, decommissioning of individual baths of the series, as well as changes in the supply voltage, necessitates the regulation of electrical parameters. To ensure the desired performance of the electrolysis plant, automatic regulation of the voltage, power and current of the series is used. The most common method of regulation is to maintain a constant current in the series.

In non-ferrous metallurgy, the most powerful electrolysis plants include a series of baths for the production of aluminum and magnesium. To obtain aluminum, electrolyzers with a voltage of 4–5 V and currents of 100–150 kA are used, the voltage of the series is 450–850 V. The operating modes of electrolysis plants are long and continuous. When taking individual baths for repair, they are shunted with special tires. According to the reliability category, the installations belong to the first category. Some of them, such as aluminum electrolysis plants, due to the large heat capacity of the baths, allow short-term (several minutes) interruptions, but a long stop can lead to solidification of the electrolyte and a significant disruption of the technological process, which may take up to 10 days to restore.

In electrochemistry, electrolyzers with voltages from 2 to 10–12 V, and in some cases up to 10–220 V are used (installations for water decomposition, made according to the principle of a filter press, in which all electrodes are connected in series). The voltages of the series of baths are 150–850 V. During the electrolysis of chlorine, the current of the baths is 100–190 kA. The operating mode of electrochemistry installations is continuous. Electrochemistry installations belong to the first category of reliability. For chlorine installations, interruptions in the power supply during start-up periods are especially dangerous.

In metal coating installations, the voltage of the baths ranges from 3.5 to 9–10 V and a maximum of 25 V. The currents of the baths vary in the range of 0.1–5 kA and higher. In most cases, regulation of the magnitude of the current over a wide range is required. The difference in the modes of operation of individual baths does not allow their sequential inclusion. Baths are most often powered from common lines with a voltage of 6–12 V through individual adjusting rheostats. Coating plants used in in-line automatic lines, belong to the receivers of the first category, separate baths - to the second category. The total power of converter units in metal plating shops is 50–200 kW. Their power source is workshop networks with a voltage of 380 V. The operating modes of the installations are cyclic, associated with loading products into baths and unloading them.

For industrial electrolysis, direct current is used. Along with traditional methods conducting electrolysis at direct current, apply modes associated with the use of currents of complex shape, periodic changes in direct current. Electrolysis installations are powered by direct current from direct current generators, including unipolar ones, and from static semiconductor converter units.

The converter unit consists of a power transformer, one, two or four rectifier units, as well as switching, control and auxiliary equipment (protection, signaling). Units with rectified current up to 6.25 kA have a valve transformer with one secondary winding, at a current of 12.5 kA - with two, at a current of 25 kA - with four windings and, accordingly, with one, two and four rectifier units (Fig. 1.1) .

Rice. 1.1.

For converter units, a six-phase zero circuit is used with the connection of the secondary windings of the transformer according to the “two reverse stars with an equalizing reactor” scheme (Fig. 1.2 a) and a three-phase bridge circuit (Fig. 1.2 b). Converter units low power are assembled according to a three-phase zero circuit (Fig. 1.2 c).

Rice. 1.2.

Most electrolysis plants require rectified voltage regulation. The need to change the voltage at the terminals of the electrolysis series in the normal mode of its operation is determined by the following reasons:

a) a change in voltage in the AC supply network;

b) a change in the number of baths in the electrolysis series due to the withdrawal of a certain number of baths for repair or shunting for technological reasons;

c) changing the operating mode of the baths, in particular, when changing the current strength or the interelectrode space.

In the starting modes of electrolysis plants, voltage regulation is usually required over a wide range. The reasons for this are, firstly, the fact that a series of electrolysis, as a rule, is not started in its entirety, but in parts or even in separate baths. Secondly, the starting mode of operation of the bath can differ significantly from the normal operating mode. So, for example, aluminum baths are fired before start-up (without electrolyte) and there is a reduced voltage on them, but in the first period after start-up, the voltage on the baths is kept higher than in normal mode.

Therefore, voltage regulation is carried out in two ways:

1. step converter transformer (TDNPV - three-phase, D - blast cooling, N - with on-load tap-changer, PV - valve converter; TMNPU-U - with surge reactor);

2. smooth regulation is carried out by a saturation throttle (DN-6300, regulation limit 49 V).

In converter substations, each valve is protected by a fast-acting fuse.

A fast-acting fuse has a current-limiting ability, i.e., the melting time FU is much less than the rise time of the short-circuit current. up to the maximum value.

The converting substation includes: alternating current switchgear, converting units and rectified current switchgear. From AC switchgear, in addition to units and transformers for auxiliary needs of converter substations, in some cases other consumers of the enterprise's electricity are also fed.

For compensation reactive power generated by converter installations, longitudinal capacitive compensation, resonant filters, multi-phase rectification circuits and compensation rectifier units are used.

Converter substations feeding electrolysis plants for the production of aluminum, magnesium and chlorine are characterized by a significant number of parallel operating rectifier units and high power.

The rectifier unit is a source of higher harmonics of current and voltage, causing deterioration in power factors and additional losses of electricity, as well as interference in communication and television channels. The degree of influence of higher harmonics is inversely proportional to the number of rectification phases. With the increase in the power of the unit, the influence increases.

An increase in the number of rectification phases leads to the disappearance of harmonic components of the order below – 1.

An increase in the number of rectification phases is achieved by special windings or by creating an equivalent multi-phase mode for groups of units, each of which operates in a six-phase rectification mode. A twelve-phase rectification scheme was adopted as the optimal one.

For other industries that have electrolyzers for a lower current, the operation of single units for each electrolysis series is typical.

With a small number (2–4) of substation AC switchgear units, it usually has a single sectioned busbar system (Fig. 1.3).

Rice. 1.3.

At large numbers converter units, preference is given to switchgear with a double busbar system (Fig. 1.4).

Rice. 1.4.

A double bus system is also preferable in terms of providing starting modes. For the majority of electrolysis installations in the starting mode, regulation of the rectified voltage is required within a significant range. If the rectifier units cannot provide the required range, then a step-down transformer is temporarily installed to further reduce the voltage, for the starting period. With two busbar systems, one of them is supplied with a reduced voltage through an autotransformer, which is necessary for converter units, and the normal voltage required for other electricity consumers is maintained on the other busbar system.

Converter substations high power usually powered by step-down transformers 220/10 kV with a capacity of 180-200 MVA, with on-site low voltage split windings. To reduce short-circuit currents. on 10 kV buses, separate operation of split windings is used.

High requirements for the uninterrupted power supply of electrolysis plants force the use of increased redundancy in their power systems, which is achieved by separating all links of the power supply system, using a double busbar system, and installing sectional switches with an ATS device.

Converting units of powerful electrolysis plants are connected to the series directly without switching equipment. Installations of relatively low power are connected using circuit breakers, which are also the protective equipment of the unit. High-current switching equipment is also used when feeding series or individual electrolyzers with current, shunting baths when extinguishing anode flashes, taking them out for repair, etc.

High-speed circuit breakers of the VAB and BAT series are used for quick trips without loads and rare trips under load. They consist of unified units-blocks, equipped with the same type of relays and control units. Switches of the BAT series differ from the VAB series by the presence of an inductive-dynamic drive. The speed of the drive is ensured by the fact that the retaining magnetic flux is displaced into a parallel section of the magnetic circuit.

Current from power sources is supplied to the electrolysis baths through special busbars, consisting of separate rectangular busbars assembled in packages. Usually busbars are made of aluminum tires, copper is used only where aluminum is unsuitable due to its low corrosion resistance.

The cross-sections of busbars are determined based on the economic current density. The calculated section of the busbar is then checked for the allowable value of voltage losses (no more than 3%), allowable heating in steady state (no higher than 343 K) and for mechanical strength.

Since the operating currents of electrolysis baths reach tens and hundreds of kiloamperes, the cross section of the busbar also turns out to be large - up to 15 dm2.

Bus ducts supplying electricity from the rectifier substations to the electrolysis shop are mounted on special overpasses. Between separate electrolysis baths inside the workshop, busbars are laid in special busbar channels covered with reinforced concrete slabs.

Features of converting substations:

1. All converter units in the substation operate in parallel on one rectified busbar system;

2. The number of transformers at powerful converter substations can reach 10-11 pieces;

3. Converting substations are located in the immediate vicinity of the electrolysis building and are made in the form of attached or stand-alone.

Attached substations:

"+" - small length of the conductor from the side of the rectified current (reduction of losses);

“–” – deterioration of cooling conditions.

Stand-alone substations: the opposite is true.

Conclusions: electrolysis is a physical and chemical process that occurs when an electric current passes through an electrolyte solution or melt. Electrolysis is used in non-ferrous and ferrous metallurgy, in electrochemistry and mechanical engineering.

Such technology as water disinfection with sodium hypochlorite has been used for more than a hundred years. She's different enough. high efficiency and does not require large labor costs, therefore sodium hydrochloride today finds application in a wide variety of industries. With it, you can:

• disinfect water in pools and artificial reservoirs for various purposes;
• disinfect natural waters, which will then be used in the organization of household water supply;
• clean wastewater from hazardous pollutants.

Therefore, modern environmentalists successfully use electrolysis plants with sodium hypochlorite in their work. And if you are faced with the task of cleaning a large volume of water from microorganisms (regardless of its purpose), you should also pay attention to the technology in question.

It should be noted that disinfection with hypochlorite makes it possible to obtain sufficiently clean and transparent water, completely devoid of pathogenic bacteria and microorganisms. However, in the case of using the technology in question, it is necessary to take some details extremely seriously. In particular, if you are cleaning pools by disinfecting water with sodium hypochlorite, you should definitely monitor the content of active chlorine in the water, as well as the pH of the medium (ideal pH will be 7.6 - 7.8).

Want to take advantage of this versatile cleaning method? Then we recommend ordering sodium hypochlorite electrolysis plants from Ecocontrol S. We have the equipment best quality, which purifies water very quickly, effectively and safely. Moreover, we offer absolutely automated electrolyzers that do not require constant monitoring by a specialist.

As practice shows, with the help of disinfection with hypochlorite, you can achieve very high performance water quality. However, this requires good equipment. And if you want to purchase it, hurry up to become a client of our company - we offer exclusively certified products and are able to guarantee its excellent quality and performance.

OSEC ® L - WALLACE & TIERNAN ® electrolysis systems.

OSEC ® L system generates sodium hypochlorite solution<1,0% через электролиз рассола, потребляя только воду, соль и электричество. Производительность до 400г/час. Полностью автоматизирована и укомплектована для быстрой установки, безопасной работы и простого обслуживания.

The OSEC® BP system produces a 0.8% sodium hypochlorite solution by electrolyzing brine using only water, salt and electricity. The system is fully automated, making it ideal for operation without constant operator supervision. Wall mounting. Available in four standard capacities ranging from 5.5 to 22 kg/day.

OSEC® B-Pak. The electrolysis system generates a 0.8% sodium hypochlorite solution by electrolyzing brine using only water, salt and electricity. On-site and on-demand production of hypochlorite eliminates the problems associated with transporting and storing liquefied chlorine or commercial sodium hypochlorite solutions. Capacity up to 5 kg/h.

The OSEC® B-PLUS system produces a 0.8% sodium hypochlorite solution by electrolysis of brine using only water, salt and electricity. OSEC® B-Plus is fully automated and packaged for fast installation, safe operation and easy maintenance. Modules are shipped pre-tested for faults, fully wired and wired. Productivity up to 40 kg/h (increase in productivity is possible).

Map with a list of objects using electrolysis plants of the OSEC type (supplied by Ecocontrol S LLC)

Industrial water electrolyzers - plants for the electrolysis of water and waste water

A special industrial electrolyser producing a 0.8% sodium hypochlorite solution can be used in the operation of a wide variety of industrial facilities, as well as public facilities. This is a highly efficient equipment used for the disinfection of drinking and waste water, fountain and pool water, natural water, etc. Moreover, electrolyzers can be very different, and often even modern membrane technologies are used in them.

For what purposes are they used?

With the help of the considered equipment it is possible to carry out:

• disinfection of drinking water,
• wastewater treatment;
• industrial water treatment;
• water treatment in fountains;
• pool water treatment.

At the same time, electrolysis of water will cost you much less than using ready-made sodium hypochlorite.

The essence of the work of modern electrolyzers

How do water electrolysis plants work? To date, they are used to produce chlorine and caustic by electrochemical method, which are then used to disinfect water. Moreover, sulfonic cationite membranes are most often used in such devices, which, due to their main features, make it possible to obtain high-quality reaction products, ensuring the efficiency and stability of the water purification process. And if you carry out wastewater electrolysis using such devices, you can count on the best end result.

Technology Benefits

Next, you need to talk about the advantages that modern industrial water electrolyzers have, and which allow this particular equipment to become more and more popular every year. These advantages include:

• financial availability, safety and simplicity of the cleaning method;
• lack of dependence on companies that are suppliers of sodium hypochlorite;
• the ability to disinfect not only water, but also water pipes;
• complete dissolution of reagents in water (due to the use of water electrolysis technology, you get the so-called "chlorine" water);
• prevent the appearance of any pathogenic bacteria, harmful fungi and algae in the water;
• complete removal of organic impurities.

Thanks to all these advantages, water electrolysis plants are very actively used in our time by a wide variety of civil, industrial and municipal facilities. And if you're also in need of highly efficient and affordable water treatment equipment, be sure to check them out. Moreover, it is most expedient to order all devices for the electrolysis of wastewater, waters of fountains, pools and other artificial reservoirs, as well as household waters, from Ecocontrol S. Our staff will competently select the best equipment for you, give professional advice, help set up and adjust the devices, provide warranty and service. And all this on the most favorable terms!

An electrolyser is a special device that is designed to separate the components of a compound or solution using an electric current. These devices are widely used in industry, for example, to obtain active metal components from ore, to purify metals, to apply metal coatings to products. For everyday life, they are rarely used, but also found. In particular, for home use, devices are offered that allow you to determine the contamination of water or get the so-called "living" water.

The basis of the operation of the device is the principle of electrolysis, the discoverer of which is considered to be the famous foreign scientist Faraday. However, the first water electrolyzer 30 years before Faraday was created by a Russian scientist named Petrov. He proved in practice that water can be enriched in the cathode or anode state. Despite this injustice, his work was not in vain and served the development of technology. At the moment, numerous types of devices have been invented and successfully used that work on the principle of electrolysis.

What is it

The electrolyzer works thanks to an external power source that supplies electric current. Simplified, the unit is made in the form of a housing in which two or more electrodes are mounted. Inside the case is an electrolyte. When an electric current is applied, the solution decomposes into the required components. Positively charged ions of one substance are directed to a negatively charged electrode and vice versa.

The main characteristic of such units is performance. That is, this is the amount of solution or substance that the installation can process in a certain period of time. This parameter is indicated in the model name. However, it can also be influenced by other indicators: current strength, voltage, type of electrolyte, and so on.

Species and types

According to the design of the anode and the location of the current conductor, the electrolyzer can be of three types, these are units with:

1. Pressed baked anodes.
2. A continuous self-baking anode, as well as a side conductor.
3. Continuous self-baking anode, as well as the upper conductor.

The electrolyzer used for solutions, according to design features, can be divided into:

• Dry.
• Flowing.
• Membrane.
• Diaphragm.

Device

The designs of the units may be different, but they all work on the principle of electrolysis.

The device in most cases consists of the following elements:

• Electrically conductive body.
• Cathode.
• Anode.
• Branch pipes designed for electrolyte input, as well as for the output of substances obtained during the reaction.

The electrodes are sealed. Usually they are presented in the form of cylinders that communicate with the external environment using nozzles. The electrodes are made of special conductive materials. A metal is deposited on the cathode or ions of the separated gas are directed to it (during the splitting of water).

In the non-ferrous industry, specialized units for electrolysis are often used. These are more complex installations that have their own characteristics. So an electrolyzer for extracting magnesium and chlorine requires a bath made of end and longitudinal walls. It is lined with refractory bricks and other materials, and is also divided by a partition into an electrolysis compartment and a cell in which the final products are collected.

The design features of each type of such equipment make it possible to solve only specific problems that are associated with ensuring the quality of released substances, the speed of the reaction, the energy intensity of the installation, and so on.

Operating principle

In electrolysis devices, only ionic compounds conduct electricity. Therefore, when the electrodes are lowered into the electrolyte and the electric current is turned on, an ionic current begins to flow in it. Positive particles in the form of cations are sent to the cathode, for example, these are hydrogen and various metals. Anions, that is, negatively charged ions flow to the anode (oxygen, chlorine).

When approaching the anode, anions lose their charge and become neutral particles. As a result, they settle on the electrode. Similar reactions occur at the cathode: cations take electrons from the electrode, which leads to their neutralization. As a result, cations settle on the electrode. For example, when water is split, hydrogen is formed, which rises up in the form of bubbles. To collect this gas, special pipes are constructed above the cathode. Through them, hydrogen enters the necessary container, after which it can be used for its intended purpose.

The principle of operation in the designs of different devices is generally similar, but in some cases there may be some peculiarities. So in membrane units, a solid electrolyte is used in the form of a membrane, which has a polymer base. The main feature of such devices lies in the dual purpose of the membrane. This interlayer can transport protons and ions, including separating electrodes and end products of electrolysis.

Diaphragm devices are used in cases where diffusion of the end products of the electrolysis process cannot be allowed. For this purpose, a porous diaphragm is used, which is made of glass, asbestos or ceramics. In some cases, polymer fibers or glass wool can be used as such a diaphragm.

Application

The electrolyzer is widely used in various industries. But, despite the simple design, it has various versions and functions. This equipment is used for:

• Mining of non-ferrous metals (magnesium, aluminum).
• Obtaining chemical elements (decomposition of water into oxygen and hydrogen, obtaining chlorine).
• Wastewater treatment (desalination, disinfection, disinfection from metal ions).
• Processing of various products (milk demineralization, salting of meat, electroactivation of food liquids, extraction of nitrates and nitrites from vegetable products, extraction of protein from algae, mushrooms and fish waste).

In medicine, the units are used in intensive care to detoxify the human body, that is, to create high-purity sodium hypochlorite solutions. For this, a flow-through device with titanium electrodes is used.

Electrolysis and electrodialysis plants are widely used to solve environmental problems and water desalination. But these units, in view of their shortcomings, are rarely used: this is the complexity of the design and their operation, the need for a three-phase current and the requirement for periodic replacement of electrodes due to their dissolution.

Such installations are also used in everyday life, for example, to obtain “living” water, as well as to purify it. In the future, it is possible to create miniature plants that will be used in cars for the safe production of hydrogen from water. Hydrogen will become a source of energy, and the car can be filled with ordinary water.