• Fuel feed
  • Fuel preparation
  • Steam production
  • Transformation of steam into mechanical energy
  • Transformation of mechanical energy into electricity
  • Voltage transformation to reduce power transmission loss
  • Distribution of electricity in different directions
Fuel feed
Fuel preparation
Steam production
Transformation of steam into mechanical energy
Transformation of mechanical energy into electricity
Voltage transformation to reduce power transmission loss
Distribution of electricity in different directions

Fuel is delivered to the power station with railway cars. During the acceptance, the quantitative control is performed – the fuel is fed into the coal charging fleet through the strain scales. At the same time, coal samples are selected and fuel quality control is performed. After that, cars with coal are fed for unloading to car dumpers or transporter cranes. In the period of low temperatures, cars with frozen coal are preliminary passed through defrosting houses of mixed type. After unloading with belt feeders and conveyors, the fuel is supplied either to raw coal silos for further processing or to a warehouse for storage. In average, thermal power plant is capable of unloading up to 200 cars with fuel every day in the summer and up to 100 cars in the winter.

Through fuel conveying system, the coal is fed into pulverization system of boiler department of thermal power plant, where it undergoes preparation for combustion - grinding and drying. These operations are performed in ball-and-drum mills: the mass of metal balls, grinding the coal, can reach up to 70 tons, and the mill drum rotates at 18 revolutions per minute. Performance of one dust system, which includes mill, separator, cyclone, mill fan, transportation and fuel supply system may reach 50 t/h, depending on the coal moisture and power unit load. The power unit of 200 MW at full load consumes up to 90 tons of coal per hour, and 800 MW power - up to 340 tons.

Milled coal in pulverized form is fed through the burners into the boiler furnace, where the combustion process takes place with heat generation.

Power boiler is a huge steam generator: the height of the boiler shell of 200 MW and 800 MW power units exceeds 40 m and 45 m, respectively, and the weight of the boiler’s metal (without structures) is between 1.1 and 1.8 thousand tons, respectively. Boilers steam-generating capacity is 640 t/h (200 MW) and 2,180 t/h (800 MW).
In the process of combustion at the core flame temperature of about 2,000 °C, flue gases assimilating most of the heat are formed. This product (with temperature of 1500-1600 °C) reacts with water, which is inside tubes and screens covering the combustion chamber’s walls from the inside. Heat exchange processes result in water boiling and water steam generation. This is saturated steam, and it is not suitable for use in the turbine due to the relatively low performance capability. To raise its temperature and hence the performance capability, it is fed to the superheater heated up with flue gases. This generates superheated steam.

Superheated steam enters the single-shaft turbine with the steam reheating stage. The weight of high, intermediate and low pressure cylinders with turbine rotors of 800 MW and 200 MW power units totals 610 t and 334 t, respectively.
Generation of mechanical energy begins with the expansion of steam flowing through the nozzle. Its pressure and temperature are reduced at the same time - from initially high parameters upstream the turbine (240 atm and 540 °C - 800 MW power unit, and 130 atm and 5,400 °C - 200 MW power unit) to the final pressure of 0.037 atm and the condenser neck temperature of 25-300 °C, while speed increases. During the condensation, the volume of steam decreases 28 thousand times. Thus, potential energy of steam is converted into kinetic energy, which is transferred to curved blades fixed on the disk rim fitted on the shaft. Blades rotate together with the disc and the shaft with frequency of 3,000 revolutions per minute, and steam energy is converted into mechanical energy.

Electric generator is a complex machine that combines electric and magnetic circuits. The weight of 800 MW and 200 MW power units’ generator reaches 515 tons and 256 tons, respectively. A generator and a steam turbine represent a single assembly. The electric generator is connected to the unified energy system via the unit transformer.
During rotation, the generator produces alternating electrical current: mechanical energy of the turbine shaft’s rotation is transferred to the generator’s shaft and is balanced by electromagnetic torque of the generator. The higher the torque on the turbogenerator shaft is, the higher the counter electromagnetic torque, and, accordingly, the current of the generator stator winding, are, which ensures the electromagnetic balance of the whole system and the equality of shaft speed and generator magnetic field. Electric power results from the electromagnetic torque and depends on the amount of steam supplied to the turbine.

An independent individual unit transformer with a certain voltage class (24/330 kV, 15.75/220 kV or 15.75/110 kV) is installed for each power unit. This equipment is intended to transform electricity and obtain parameters necessary for transmitting it over long distances with an acceptable level of losses: 15.75-24 kV voltage rises to 220-330 kV, and sometimes up to 750 kV.
Electrical and steam flow circuits are provided for the power plant's auxiliary equipment to ensure smooth functioning of the plant in normal and emergency modes. Auxiliary electricity consumption needs are met from operating and standby auxiliary transformers. Control, protection and emergency power supply of critical 0.4 kV auxiliary connections are provided from accumulator batteries.

The distribution of energy among consumers is carried out through open and closed switchgears with the help of electrical apparatus. Open switchgear and closed switchgear with voltage class of 35 kV 110 kV, 220 kV and 330 kV interconnected with autotransformers are used in power stations. Issuance of power is carried out by high-voltage lines of 330 kV, 220 kV, 110 kV and 35 kV overhead lines: the greater the distance for transferring electrical energy, the higher voltage class. Sophisticated branched electrical networks provide convenience and reliability of the power distribution between users.