Technical features of electricity generation at TPPs. Production, transmission and distribution of electrical energy. Technological process of CHP

To make the gas burn better, draft mechanisms are installed in the boilers. Air is supplied to the boiler, which serves as an oxidizing agent in the process of gas combustion. To reduce the noise level, the mechanisms are equipped with silencers. Flue gases formed during the combustion of fuel are discharged into the chimney and dispersed in the atmosphere.

The hot gas rushes through the flue and heats the water passing through the special tubes of the boiler. When heated, the water turns into superheated steam, which enters the steam turbine. Steam enters the turbine and begins to rotate the turbine blades, which are connected to the generator rotor. Steam energy is converted into mechanical energy. In the generator, mechanical energy is converted into electrical energy, the rotor continues to rotate, creating an alternating electric current in the stator windings.

Through a step-up transformer and a step-down transformer substation, electricity is supplied to consumers through power lines. The steam exhausted in the turbine is sent to the condenser, where it turns into water and returns to the boiler. At the thermal power plant, water moves in a circle. Cooling towers are designed to cool water. The CHP uses fan and tower cooling towers. Water in cooling towers is cooled by atmospheric air. As a result, steam is released, which we see above the cooling tower in the form of clouds. The water in the cooling towers rises under pressure and falls like a waterfall down into the fore-chamber, from where it flows back to the CHP. To reduce droplet entrainment, the cooling towers are equipped with water traps.

Water supply is provided from the Moscow River. In the chemical water treatment building, water is purified from mechanical impurities and enters the filter groups. On some of them, it is prepared to the level of purified water to feed the heating system, on others - to the level of demineralized water and goes to feed the power units.

The cycle used for hot water supply and district heating is also closed. Part of the steam from the steam turbine is sent to the water heaters. Further hot water is sent to heating points, where heat is exchanged with water coming from houses.

High-class specialists of Mosenergo support the production process around the clock, providing the huge metropolis with electricity and heat.

How does a combined cycle power unit work

K category: Electric installation work

Production of electrical energy

Electrical energy (electricity) is the most advanced form of energy and is used in all spheres and branches of material production. Its advantages include the possibility of transmission over long distances and conversion into other types of energy (mechanical, thermal, chemical, light, etc.).

Electrical energy is generated at special enterprises - power stations that convert other types of energy into electrical energy: chemical, fuel, water, wind, solar, nuclear.

The ability to transmit electricity over long distances makes it possible to build power plants near fuel locations or on high-water rivers, which is more economical than transporting large amounts of fuel to power plants located near electricity consumers.

Depending on the type of energy used, there are thermal, hydraulic, nuclear power plants. Power plants that use wind energy and the heat of sunlight are still low-power sources of electricity that do not have industrial significance.

Thermal power plants use thermal energy obtained by burning solid fuels (coal, peat, oil shale), liquid (fuel oil) and gaseous (natural gas, and blast-furnace and coke oven gas) in boiler furnaces.

Thermal energy is converted into mechanical energy by the rotation of the turbine, which is converted into electrical energy in a generator connected to the turbine. The generator becomes a source of electricity. Thermal power plants are distinguished by the type of primary engine: steam turbine, steam engine, internal combustion engine, locomobile, gas turbine. In addition, steam turbine power plants are divided into condensing and cogeneration. Condensing stations supply consumers only with electrical energy. The exhaust steam goes through a cooling cycle and, turning into condensate, is again fed into the boiler.

The supply of consumers with thermal and electrical energy is carried out by heating stations, called combined heat and power plants (CHP). At these stations, thermal energy is only partially converted into electrical energy, and is mainly spent on supplying industrial enterprises and other consumers located in the immediate vicinity of power plants with steam and hot water.

Hydroelectric power plants (HPPs) are built on rivers, which are an inexhaustible source of energy for power plants. They flow from highlands to lowlands and are therefore capable of doing mechanical work. Hydroelectric power stations are built on mountain rivers using the natural pressure of water. On flat rivers, the pressure is artificially created by the construction of dams, due to the difference in water levels on both sides of the dam. Hydro turbines are the primary engines in hydroelectric power plants, in which the energy of the water flow is converted into mechanical energy.

Water rotates the impeller of the hydroturbine and the generator, while the mechanical energy of the hydroturbine is converted into electrical energy generated by the generator. The construction of a hydroelectric power station, in addition to the task of generating electricity, also solves a complex of other tasks of national economic importance - improving the navigation of rivers, irrigating and watering arid lands, improving water supply to cities and industrial enterprises.

Nuclear power plants (NPPs) are classified as thermal steam turbine stations that do not operate on fossil fuels, but use as an energy source the heat obtained in the process of nuclear fission of nuclear fuel (fuel) atoms - uranium or plutonium. At nuclear power plants, the role of boiler units is performed by nuclear reactors and steam generators.

Power supply to consumers is carried out mainly from electrical networks that combine a number of power plants. Parallel operation of power plants on a common electrical network provides a rational distribution of the load between power plants, the most economical generation of electricity, better use of the installed capacity of stations, increasing the reliability of power supply to consumers and supplying them with electricity with normal quality indicators in terms of frequency and voltage.

The need for unification is caused by the unequal load of power plants. Consumer demand for electricity changes dramatically not only during the day, but also at different times of the year. In winter, electricity consumption for lighting increases. In agriculture, electricity is needed in large quantities in summer for field work and irrigation.

The difference in the degree of loading of the stations is especially noticeable with a significant distance between the areas of electricity consumption from each other in the direction from east to west, which is explained by the difference in the timing of the hours of morning and evening load maxima. In order to ensure the reliability of power supply to consumers and make better use of the power of power plants operating in different modes, they are combined into energy or electrical systems using high-voltage electrical networks.

The set of power plants, power lines and heat networks, as well as receivers of electricity and heat energy, connected into one unit by the commonality of the regime and the continuity of the process of production and consumption of electricity and heat, is called the energy system (energy system). The electrical system, consisting of substations and transmission lines of various voltages, is part of the power system.

The energy systems of individual regions, in turn, are interconnected for parallel operation and form large systems, for example, the unified energy system (UES) of the European part of the USSR, the unified systems of Siberia, Kazakhstan, Central Asia, etc.

Combined heat and power plants and factory power plants are usually connected to the power grid of the nearest power system via generator voltage lines of 6 and 10 kV or higher voltage lines (35 kV and higher) through transformer substations. The transmission of energy generated by powerful regional power plants to the power grid for supplying consumers is carried out via high voltage lines (110 kV and higher).

« Physics - Grade 11 "

Power generation

Electricity is produced at power stations mainly with the help of electromechanical induction generators.
There are two main types of power plants: thermal and hydroelectric.
These power plants differ in engines that rotate the rotors of generators.

At thermal power plants, the source of energy is fuel: coal, gas, oil, fuel oil, oil shale.
The rotors of electric generators are driven by steam and gas turbines or internal combustion engines.

Thermal steam turbine power plants - TPPs the most economical.

In a steam boiler, over 90% of the energy released by the fuel is transferred to steam.
In the turbine, the kinetic energy of the steam jets is transferred to the rotor.
The turbine shaft is rigidly connected to the generator shaft.
Steam turbine generators are very fast: the number of revolutions of the rotor is several thousand per minute.

The efficiency of heat engines increases with an increase in the initial temperature of the working fluid (steam, gas).
Therefore, the steam entering the turbine is brought to high parameters: the temperature is almost up to 550 ° C and the pressure is up to 25 MPa.
The efficiency of TPP reaches 40%. Most of the energy is lost along with the hot exhaust steam.

Thermal power plants - CHP allow a significant part of the energy of the exhaust steam to be used in industrial enterprises and for domestic needs.
As a result, the CHP efficiency reaches 60-70%.
In Russia, thermal power plants provide about 40% of all electricity and supply hundreds of cities with electricity.

On hydroelectric power plants - HPPs the potential energy of water is used to rotate the rotors of the generators.

The rotors of electric generators are driven by hydraulic turbines.
The power of such a station depends on the pressure created by the dam and the mass of water passing through the turbine every second.

Hydroelectric power plants provide about 20% of all electricity generated in our country.

Nuclear power plants - nuclear power plants in Russia they provide about 10% of electricity.

Electricity use

The main consumer of electricity is industry - 70% of the electricity produced.
Transport is also a major consumer.

Most of the electricity used is now converted into mechanical energy, because. almost all mechanisms in industry are driven by electric motors.

Electricity transmission

The transmission of electricity is associated with noticeable losses, since the electric current heats the wires of power lines. In accordance with the Joule-Lenz law, the energy spent on heating the wires of the line is determined by the formula

Where
R- line resistance,
U- transmitted voltage,
R- power of the current source.

With very long lines, power transmission can become uneconomical.
It is practically very difficult to significantly reduce the resistance of the line R, therefore, it is necessary to reduce the current strength I.

Since the power of the current source P is equal to the product of the current I and the voltage U, in order to reduce the transmitted power, it is necessary to increase the transmitted voltage in the transmission line.

For this, step-up transformers are installed at large power plants.
The transformer increases the voltage in the line as many times as it reduces the current.

The longer the transmission line, the more advantageous it is to use a higher voltage. Alternating current generators are tuned to voltages not exceeding 16-20 kV. Higher voltage would require complex special measures to isolate the windings and other parts of the generators.

This is achieved using step-down transformers.

The decrease in voltage (and, accordingly, the increase in current strength) is carried out in stages.

At very high voltage between the wires, a discharge can begin, leading to energy losses.
The permissible amplitude of the alternating voltage must be such that, for a given cross-sectional area of ​​the wire, the energy loss due to the discharge is negligible.

Power stations are connected by high-voltage transmission lines, forming a common electrical network to which consumers are connected.
Such an association, called a power system, makes it possible to distribute the loads of energy consumption.
The power system ensures uninterrupted power supply to consumers.
Now the Unified Energy System of the European part of the country is operating in our country.

Electricity use

The need for electricity is constantly increasing both in industry, in transport, in scientific institutions, and in everyday life. This need can be met in two main ways.

The first is the construction of new powerful power plants: thermal, hydraulic and nuclear.
However, the construction of a large power plant requires several years and high costs.
In addition, thermal power plants consume non-renewable natural resources: coal, oil and gas.
At the same time, they cause great damage to the balance on our planet.
Advanced technology makes it possible to meet energy needs in a different way.

The second is the efficient use of electricity: modern fluorescent lamps, lighting savings.

Great hopes are placed on obtaining energy by means of controlled thermonuclear reactions.

Priority should be given to increasing the efficiency of electricity use, rather than increasing the capacity of power plants.

Production (Generation) of electricity is the process of converting various types of energy into electrical energy at industrial facilities called power plants. Currently, there are the following types of generation:

Thermal power industry. In this case, the thermal energy of combustion of organic fuels is converted into electrical energy. The thermal power industry includes thermal power plants (TPPs), which are of two main types:

Condensing (IES, the old abbreviation GRES is also used). Condensation is called non-combined generation of electrical energy;

Heating plants (thermal power plants,CHP). Cogeneration is the combined generation of electrical and thermal energy at the same station;

IES and CHP have similar technological processes. In both cases, there isboiler, in which fuel is burned and due to the heat released, steam is heated under pressure. The heated steam is then fed intosteam turbine, where its thermal energy is converted into rotational energy. The turbine shaft rotates the rotorgenerator- in this way, the rotational energy is converted into electrical energy, which is fed into the network. The fundamental difference between CHP and IES is that part of the steam heated in the boiler goes to heat supply needs;

Nuclear energy. It includes nuclear power plants (NPPs). In practice, nuclear power is often considered a subspecies of thermal power, since, in general, the principle of generating electricity at nuclear power plants is the same as at thermal power plants. Only in this case, thermal energy is released not during the combustion of fuel, but during the fission of atomic nuclei intonuclear reactor. Further, the scheme for generating electricity is not fundamentally different from a thermal power plant: steam is heated in a reactor, enters a steam turbine, etc. Due to some design features, nuclear power plants are unprofitable to use in combined generation, although separate experiments in this direction were carried out;

hydropower. It includes hydroelectric power plants (HPP). In hydropower, the kinetic energy of water flow is converted into electrical energy. To do this, with the help of dams on rivers, a difference in the levels of the water surface is artificially created (the so-called upper and lower pools). Water under the action of gravity overflows from the upstream to the downstream through special channels in which water turbines are located, the blades of which are spun by the water flow. The turbine rotates the rotor of the generator. Pumped-storage stations (PSPPs) are a special type of hydroelectric power station. They cannot be considered generating capacities in their pure form, since they consume almost as much electricity as they generate, but such stations are very effective in unloading the network during peak hours;

alternative energy. It includes methods of generating electricity that have a number of advantages compared to the "traditional" ones, but for various reasons have not received sufficient distribution. The main types of alternative energy are:

Wind power- the use of kinetic energy of the wind to generate electricity;

Solar energy- obtaining electrical energy from the energy of sunlight;

Common disadvantages of wind and solar energy are the relative low power of generators with their high cost. Also, in both cases, storage capacities are required for night (for solar energy) and calm (for wind energy) time;

geothermal energy- use of natural heatEarthfor generating electrical energy. In fact, geothermal stations are ordinary thermal power plants, where the source of heat for heating steam is not a boiler or a nuclear reactor, but underground sources of natural heat. The disadvantage of such stations is the geographical limitations of their application: it is cost-effective to build geothermal stations only in regions of tectonic activity, that is, where natural heat sources are most accessible;

Hydrogen energy- usagehydrogenasenergy fuelhas great prospects: hydrogen has a very highefficiencycombustion, its resource is practically unlimited, the combustion of hydrogen is absolutely environmentally friendly (the product of combustion in an oxygen atmosphere is distilled water). However, hydrogen energy is currently not able to fully satisfy the needs of mankind due to the high cost of producing pure hydrogen and the technical problems of its transportation in large quantities;

It is also worth noting alternative forms of hydropower: tidalAndwaveenergy. In these cases, the natural kinetic energy of marinetidesand windwavesrespectively. The spread of these types of electric power industry is hindered by the need for too many factors to coincide when designing a power plant: not just a sea coast is needed, but a coast on which the tides (and sea waves, respectively) would be sufficiently strong and constant. For example, the coastBlack Seanot suitable for the construction of tidal power plants, since the differences in the water level of the Black Sea at high and low tide are minimal.