Production of electrical energy at a power plant. Technological process of thermal power plant. Nuclear power plants in Russia

Electricity, as the fundamental engine of the development of civilization, entered the life of mankind relatively recently. The active use of electricity began just over a hundred years ago.

History of the world electric power industry

Electric power industry is a strategic sector of the economic system of any state. The history of the emergence and development of energy efficiency begins with late XIX centuries. The forerunner of the emergence of industrial electricity generation was the discovery of fundamental laws about the nature and properties of electric current.

The starting point when the production and transmission of electricity arose is considered to be 1892. It was then that the first power plant was built in New York under the leadership of Thomas Edison. The station became a source of electric current for street lighting lamps. This was the first experience in converting thermal energy from coal combustion into electricity.

Since then, the era of mass construction of thermal power plants (TPPs) operating on solid fuel - thermal coal - has begun. With the development of the oil industry, huge reserves of fuel oil appeared, which were formed as a result of the refining of petroleum products. Technologies have been developed for obtaining a carrier of thermal energy (steam) from burning fuel oil.

Since the thirties of the last century, hydroelectric power plants (HPPs) have become widespread. Enterprises began to use the energy of falling water flows from rivers and reservoirs.

In the 70s, rapid construction of nuclear power plants (NPPs) began. At the same time, alternative sources of electricity began to be developed and implemented: wind turbines, solar panels, and alkaline-acid geostations. Mini installations have appeared that use heat to generate electricity as a result of chemical processes of decomposition of manure and household waste.

History of Russian electric power industry

A powerful impetus for the development of electrical energy production was the adoption by the young state of the USSR of the GOELRO plan in 1920. It was decided to build 10 power plants with a total capacity of 640 thousand kW over 15 years. However, by 1935, 40 state regional power plants (GRES) had been commissioned. A powerful base for the industrialization of Russia and the Union republics was created.

In the 1930s, mass construction of hydroelectric power stations (HPPs) began on the territory of the USSR. The rivers of Siberia were developed. The famous Dnieper Hydroelectric Power Station was built in Ukraine. In the post-war years, the state paid attention to the construction of hydroelectric power stations.

Important! The emergence of cheap electricity in Russia solved the problem of urban transport in large regional centers. Trams and trolleybuses not only became an economic incentive for the use of electricity in transport, but also brought a significant reduction in liquid fuel consumption. Cheap energy resources have led to the emergence of railways electric locomotives

In the 70s, as a result of the global energy crisis, there was a sharp increase in oil prices. A nuclear energy development plan has begun to be implemented in Russia. Almost all republics of the Soviet Union began to build nuclear power plants. Today's Russia has become the leader in this regard. Today there are 21 nuclear power plants operating on the territory of the Russian Federation.

Basic technological processes in the electric power industry

Electricity production in Russia is based on three pillars of the energy system. These are nuclear, thermal and hydropower.

Three types of electricity generation

Electric power industries

The list of industrial sources of electrical energy production consists of 4 energy sectors:

• atomic;
• thermal;
• hydropower;
• alternative.

Nuclear energy

This energy production industry is today the most in an efficient way generating electricity through a nuclear reaction. For this purpose, purified uranium is used. The heart of the station is the nuclear reactor.

The heat sources are fuel elements (fuel elements). They are thin, long zirconium tubes containing uranium tablets. They are combined into groups - fuel assembly (fuel assembly). They load the reactor vessel, in the body of which there are pipes with water. During the nuclear decay of uranium, heat is released, which heats the water in the primary circuit to 3200.

The steam flows to turbine blades, which rotate alternating current generators. Electricity enters the general energy system through transformers.

Pay attention! Remembering the Chernobyl tragedy, scientists around the world are improving the safety system of nuclear power plants. The latest developments in nuclear energy ensure that nuclear power plants are almost 100% harmless.

Thermal energy

Thermal power plants operate on the principle of burning natural fuels: coal, gas and fuel oil. Water passing through pipelines through boilers is converted into steam and is subsequently supplied to the blades of generator turbines.

Additional information. Over 4 years of operation of one group of fuel rods, such an amount of electricity is generated that the thermal power plant will need to burn 730 natural gas tanks, 600 coal cars or 900 oil railway tankers.

In addition, thermal power plants greatly worsen the environmental situation in the areas where they are located. Fuel combustion products heavily pollute the atmosphere. Only stations operating on gas turbine units meet the requirements of environmental cleanliness.

Hydropower

Examples of the effective use of hydropower are the Aswan, Sayano-Shushenskaya hydroelectric power stations, etc. The most environmentally friendly power plants that use the kinetic energy of water movement do not produce any harmful emissions into the environment. However, the mass construction of hydraulic structures is limited by a combination of circumstances. This is the presence of a certain amount of natural water flow, a feature of the terrain, and much more.

Alternative energy

The scientific and technological revolution does not stop for a minute. Every day brings innovations in the production of electric current. Inquiring minds are constantly busy searching for new technologies for generating electricity, which act as an alternative to traditional methods of generating electricity.

Mention should be made of wind generators, tidal sea stations and solar panels. Along with this, devices appeared that generate electric current using the heat of decomposition of household waste and livestock waste products. There are devices that use the temperature difference between different layers of soil, the alkaline and acidic environment of the soil at different levels. Alternative sources of electricity have one thing in common - this is the incomparability of the amount of energy generated with the amount of electricity that is obtained by traditional methods (nuclear power plants, thermal power plants and hydroelectric power plants).

Electrical energy transmission and distribution

Regardless of the design of power plants, their energy is supplied to the country’s unified energy system. The transmitted electricity enters distribution substations, and from there it reaches the consumers themselves. Electricity is transferred from producers by air via power lines. For short distances, current flows in a cable that is laid underground.

Electrical energy consumption

With the advent of new industrial facilities and the commissioning of residential complexes and civil buildings, electricity consumption is increasing every day. Almost every year, new power plants come into operation in Russia, or existing enterprises are replenished with new power units.

Types of activities in the electric power industry

Electric companies are engaged in the uninterrupted delivery of electricity to every consumer. In the energy sector, the employment level exceeds that of some leading sectors of the state's national economy.

Operational dispatch control

TAC plays a critical role in the redistribution of energy flows in an environment of changing consumption levels. Dispatch services are aimed at transmitting electric current from the manufacturer to the consumer in trouble-free mode. In the event of any accidents or failures in power lines, the ODU performs the duties of the operational headquarters for quick elimination these shortcomings.

Energosbyt

Tariffs for payment for electricity consumption include costs for the profits of energy companies. The correctness and timeliness of payment for consumed services is monitored by the Energosbyt service. The financial support of the entire energy system of the country depends on it. Penalties are applied to non-payers, up to and including disconnecting the consumer's power supply.

The energy system is the circulatory system of a single organism of the state. Electricity production is a strategic area for the security of existence and development of the country’s economy.

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The choice of a scenario for sustainable and safe energy development for any state should be made taking into account global global problems: climate change, the need to choose sustainable or crisis economic development, ensuring the normal functioning of the population, strengthening energy saving policies, since almost a third of all extracted energy resources are currently being lost, which leads not only to economic, but also to environmental damage.

In the long term, the development of the economy and energy will be determined by a combination of three principles - static, cyclical and dynamic. According to the static principle, until 2050 the inertia of economic and energy development will prevail. The cyclical principle establishes that along with this there must be a cyclical nature of energy and economic development. The dynamic principle leads us to expect an acute complex crisis, which will most likely be resolved by a complete change in the directions and standards of energy development.

According to expert forecasts, in European countries the demand for electricity in 2030 will vary from 244 TWh (pessimistic scenario) to 315 TWh (optimistic scenario). Under the base scenario, electricity demand will reach 282 TWh by 2030, which is 50% higher than the 2010 level (191 TWh). This will be mainly due to an increase in energy consumption in industry (by 40%) and in the service sector (by 100%).

The main directions of work to ensure energy efficiency of electricity generation processes are as follows:

1. reduction of production costs and reduction of electricity losses in solar power plants for industrial and household consumers, as well as losses due to low metrological characteristics of electricity metering devices;
2. reducing the probability of EO failure in the event of man-made and natural emergencies;
3. increasing the reliability of power equipment, reducing operating costs for maintenance, high-quality and modern diagnostics of its technical condition;
4. increasing the efficiency of the use of electrical and thermal energy in the public sector and in social, administrative and cultural facilities;
5. complete supply of modern, energy-saving electrical equipment to PPs and power plants, introduction of new achievements of science and technology, modern technologies.

According to the method of generating electricity, they are distinguished:

• thermal power plants (CHP, CHP), using the combustion energy of natural fossil fuels (coal, gas, fuel oil);
• hydraulic (HPP) and pumped storage power plants (PSPP), using the energy of falling water;
• nuclear power plants (NPPs) that use nuclear decay energy;
• diesel power plants (DES);
• Thermal power plants with gas turbine (GTU) and combined cycle gas units (CCP);
• solar power plants (SP);
• wind power plants (WPP);
• geothermal power plants (geo-thermal power plants);
• tidal power plants (TPP).

In table 1 presents data on the current and future structure of electricity generation in the United Energy System (IPS) of Ukraine, which takes into account installed, maneuverable and reserve capacities.

Table 1 – Data on the current and future structure of electricity production in the unified energy system of Ukraine

*Partial load operation

Maneuverable and reserve capacities are necessary to ensure stable operation of the energy system during periods of “peaks” and “troughs” of energy consumption during the day and depending on the time of year. These data currently need to be taken into account, because The daily difference in electricity consumption in the daily load schedule of SES in Ukraine reaches 8000 MW, and the seasonal difference (winter - summer) is 5000 MW.

The most effective maneuverable capacities in the UES of Ukraine are turbogenerators (TG) of thermal power plant units and hydrogenerators of hydroelectric power plants (PSPP).

2. Technological processes for generating electricity at thermal power plants (CHP and CHP)

Approximately 70% of the world's electricity is generated in classical thermal power plants. They are divided into condensing thermal power plants (CHPs, more often called TPPs), which produce mainly electricity, and combined heat and power plants (CHPs), which produce electricity, as well as hot water to provide consumers and heating.

Thermal power plants and thermal power plants use non-renewable fuel (coal, gas, fuel oil, peat), mainly coal. In the near future, coal technologies will continue to play a predominant role in the electricity sector, and investment in this area will increase. Therefore, the main directions of scientific research should be work to reduce CO2 emissions.

The main equipment of a thermal power plant is a boiler, a steam generator, a turbine, a heat generator, and pumping equipment. In a boiler, when fuel is burned, thermal energy is released, which is transferred to water and converted into water vapor energy in a steam generator. Steam from the steam generator enters the turbine, where its thermal and kinetic energy is converted into mechanical energy of rotation of the turbine and the TG rotor. In a turbogenerator, mechanical energy is converted into electrical energy. Thus, the process of generating electricity at thermal power plants can be divided into three cycles:

1. chemical - combustion process, as a result of which thermal energy is transferred to water and steam;
2. mechanical – the thermal energy of steam is converted into mechanical energy of rotation of the turbine and generator rotor;
3. electrical – TG converts mechanical energy into electrical energy.

The overall efficiency of a thermal power plant is determined by the product of the efficiency (η) of these cycles:

The efficiency of a mechanical cycle is determined by the Carnot cycle:

Where T 1 and T 2 – steam temperature at the inlet and outlet of the steam turbine.

At modern thermal power plants T 1= 550 °C (823 K), T 2 = 23 °C (296 K).

As a result: ηTES≈0.9·0.9·0.64·100%=0.52·100%=52%.

On average, the efficiency of thermal power plants is 50%. At thermal power plants, thanks to the additional use of thermal energy, the efficiency is slightly higher and equals 60-65%.

In Fig. Figure 1 shows a diagram of electricity production at thermal power plants. The technological cycle for generating electricity and heat at a thermal power plant is shown in Fig. 2. A special feature of thermal power plants is a fairly large power of the thermal cycle along with electrical power, and greater electricity consumption for its own needs than at thermal power plants.

Figure 1 – 1 – fuel storage and fuel supply system, 2 – fuel preparation system, 3 – boiler, 4 – turbine, 5 – condenser, 6 – circulation pump, 7 – condensate pump, 8 – feed pump, 9 – boiler burners, 10 – fan, 11 – smoke exhauster, 12 – air heater, 13 – water economizer, 14 – low pressure heater, 15 – deaerator, 16 – high pressure heater

Figure 2 – 1 – network pump; 2 – network heater

3. Technological process for generating electricity at thermal power plants with gas turbine units

At thermal power plants with gas turbine units (GTU), the working fluid is a heated mixture of gas and air, i.e. the fuel combustion cycle is excluded. The gas-air mixture heated to a temperature of +750÷770 °C is supplied to the turbine blades, which rotates the generator rotor. TPPs with gas turbines are more maneuverable, easy to start, stop, and regulate, therefore they can be used as maneuverable power to regulate the power factor (cosφ) of the power system.

Industrial gas turbines are one of the main components of the fuel and energy complexes (FEC) of many countries around the world. Today, more than 65% of new electricity generating capacities are based on the use of gas turbine units and gas turbine thermal power plants, which are superior to coal thermal power plants in many respects. Gas turbine units of thermal power plants have high efficiency and operational reliability. They are produced all over the world, provided with after-sales service, used in a wide range of capacities, used for both nominal loads and peak load coverage.

For modern gas turbines, the cost of 1 kW of installed capacity is $400–700; for combined cycle power plants – about $1,000 (The cost of 1 kW of installed capacity at thermal power plants has already exceeded $1,200). But the power of gas turbine plants and gas turbine thermal power plants is 5–8 times less than the installed capacity of steam thermal power plants and thermal power plants.

The total number of gas turbines that have already been installed and will be installed in the world by 2020 will exceed 12 thousand units. However, since 2015, the production rate of gas turbines has decreased to 1,206 units per year compared to the production of 1,337 units in 2011, which is explained by the increased development of nuclear power plants new generation, more active use of industrial and household waste for energy production, development of bioenergy, as well as the increasing use of wind and solar energy.

4. Technological process for generating electricity at low-power power plants of block-modular design (BMI)

Promising technologies for generating thermal and electrical energy include energy obtained by using unclaimed industrial waste (gases). At mining and metallurgical enterprises for generator sets BMI, arranged according to the “turbine – gearbox – generator” scheme, uses a mixture of blast furnace and converter gases as fuel (the caloric content of the mixture is regulated with coke oven gas), as well as unclaimed steam from waste heat boilers and cooling systems of the main metallurgical equipment. Such sources are usually not connected to the general industrial network, but are used to supply autonomous consumers.

As the experience of European countries has shown, to provide electricity to small and medium-sized substations, it is promising to use low-power BMI power plants (0.5 - 30.0 MW), the production of which has been established in various European companies: in G-Team a.s.. (Czech Republic), Capstone Turbine Corporation(USA), JFE Engineering Corporation(Germany), Turbec(Italy), GC "Turbopar" (Russia), Dresser Rand(France), OPRA Technologies(Netherlands).

The disadvantages of BMI power plants include relatively low efficiency, variable frequency and voltage of the generated electricity, and non-sinusoidal current. But BMI power plants also have a number of advantages that allow us to consider their use promising:

• unclaimed, usually lost, resources are used: fuel waste, steam, industrial gases, low-cost renewable resources;
• The use of BMI power plants has a positive impact on the environment: they use gases (CO, CO2, SO2, NOx) and steam released during the metallurgical production process as fuel, excluding their emissions into the air and water basins. There is also no need to build dams, as for hydroelectric power plants or pumped storage power plants, and, accordingly, to flood the territories;
• BMI power plants are placed in close proximity to the fuel (gas) source;
• the use of small BMI power plants increases the number of jobs and reduces the unemployment rate.

A unit from the company " Mitsubishi", which combines a fuel gas compressor, a combined gas/steam turbine and a TG. All equipment is installed on one shaft. The compressor and turbine are connected to the TG shaft through an overdrive gear.

During operation, the following positive aspects of using TUES were noted:

1. energy costs of the enterprise were reduced due to self-sufficiency in fuel - gases from own production(converter, blast furnace and coke oven gases), usually sent for flaring;
2. Emissions of harmful metallurgical gases (CO, CO2, SO2, NOx) have been almost completely eliminated, which has improved the environmental condition of the region.

5. Technological process for generating electricity at a mini-CHP (mini-CHP)

The main purpose of mini-CHP is to provide electricity, heat and hot water to small industrial facilities and the population. Depending on the type of fuel, gas piston, steam turbine and combined cycle gas plants with a capacity from 200 kW to 850 MW are installed at mini-CHPs. The advantages of mini-CHP include maximum proximity to consumers and the ability to use a wide variety of fuels: gas, fuel oil, coal, wood chips and waste, peat, sunflower husks, flax husks, municipal solid waste, industrial poultry waste, etc.

The mini-CHP consists of two main departments: the steam power shop and the turbogenerator shop. In Fig. Figure 3 shows a diagram of the arrangement of equipment at a mini-CHP with a capacity of 6 MW.

The steam power shop includes a boiler house building, where steam or thermal oil boilers are installed with a firebox for different fuels, with a rustling bar and a vortex afterburning system (secondary blast system), as well as auxiliary equipment for generating stable steam.

The fuel bunker is usually located outside the main building, allowing fuel to be loaded from the warehouse by a forklift, grader or conveyors.

A

Figure 3 – A And b) with an electrical power of 6 MW and a view of the mini-CHP unit inside ( V)

The hopper is made of metal, the feeding device is a moving bottom, which carries out reciprocating movement using hydraulic cylinders and automatic fuel supply. Chimneys of mini-CHPs are designed on the basis of technical specifications (TOR) approved by the customer.

The turbogenerator shop is located in the same building as the steam power shop; it includes a steam turbine, TG, electric power section, transformers, automation and protection systems, as well as a diesel generator, which is used to run a mini-CHP.

The advantages of mini-CHP, in addition to those mentioned above, include:

• independence from hydrocarbon fuel suppliers;
• minimal dimensions of power units, full automation and convenient operation, the possibility of rapid construction and installation, which significantly reduces the amount of investment costs;
• the service life and operational reliability of a multi-fuel mini-CHP reaches 25–30 years;
• sufficiently high efficiency of power units, determined by ensuring efficient combustion of fuel even of low quality, operational safety;
• The package includes sufficiently large warehouses or fuel storage bins, which are calculated depending on the rated power of the boiler house/CHP. Such reserves ensure stable operation of mini-CHP.

Mini-CHPs are becoming increasingly widespread in many regions of Ukraine. Thus, in the Kharkov region they found a way to refuse expensive gas for heating and power supply to the population, replacing it with agricultural waste, which is used as fuel at an installed mini-CHP. Since 2017, work has been underway in Ukraine on the construction of ten mini-CHPs, the fuel for which will be straw, wood chips, stems and sunflower husks, Fig. 4.

Figure 4 –

Mini-CHPs are relevant for areas that have large volumes of household waste, agricultural and forestry waste. In addition, they not only provide industry and the population with thermal and electrical energy, but also create new jobs.

6. Technological process for generating electricity at nuclear power plants

The first nuclear reactor was built and launched in December 1942 in the USA under the leadership of E. Fermi. The first reactor built outside the United States was ZEEP, launched in Canada on September 05, 1945. In the USSR, work on nuclear energy was headed by the talented scientist Igor Kurchatov, who in 1943 created a research center in Moscow (Laboratory No. 2), which was later transformed into the Institute of Atomic Energy. In December 1946, the first chain reaction was carried out at the F1 experimental nuclear reactor, whose power was about 100 W. The first industrial reactor with a capacity of 5 MW was launched in May 1954 in Obninsk, and in June of the same year the nuclear power plant produced its first current.

The main issues when designing power reactors for nuclear power plants were:

• choice of reactor type (fast or slow neutrons);
• selection of the type of neutron moderator (graphite, “heavy” or boron-containing water);
• selection of coolant (water, gas, liquid metal) and its characteristics (temperature and pressure), measures to increase efficiency;
• ensuring personnel safety.

Already at the first nuclear power plant, automatic and manual devices were used. remote control, control rods for emergency stop reactor, devices were created to replace fuel elements (fuel elements).

A nuclear reaction begins when a critical mass of fissile material (uranium) is reached, which “burns out” during reactor operation. Therefore, it was necessary to calculate the fuel supply that would ensure the operation of the reactor for a given time. The reaction was regulated by graphite rods that absorbed excess neutrons. To maintain the power of the reactor, as the fuel burned out, the control rods were slightly pulled out of the core and installed in such a position that the reactor was on the verge of a chain reaction, but so that the active fission of uranium nuclei continued and the process remained controllable. Emergency protection rods were also provided, the complete introduction of which into the core instantly extinguished the chain reaction.

The nuclear energy industry of Ukraine begins its history in 1977, when the first unit with a single-circuit reactor RBMK-1000 was launched at the Chernobyl Nuclear Power Plant (ChNPP), Fig. 5, (power 1000 MW).

Figure 5 – NPP unit with single-circuit reactor RBMK-1000

By the 90s of the twentieth century, Ukraine already had five nuclear power plants, with 19 power units operating, and 5 power units were under construction. After the accident at the 4th block of the Chernobyl Nuclear Power Plant, the Supreme Council of Ukraine adopted the Resolution “On the moratorium on the construction of new nuclear power plants on the territory of the Ukrainian SSR” (02.08.1990). Start-up work was stopped at the 6th unit of the Zaporozhye NPP (ZAPS), at the Rivne NPP (RNPP) and the Khmelnytsky NPP (Khmelnitsky NPP), the construction of four more VVER-1000 units was stopped, two of which were in high degree readiness. It was decided to completely close the Chernobyl nuclear power plant by 2000.

However, when burning 1 kg of coal, you can get 8 kWh of electricity, and when consuming 1 kg of nuclear fuel, you can get 23 million kWh of electricity. Therefore, the decommissioning of the Chernobyl NPP and the refusal to build new units (with a prospective assessment of the growth of energy consumption in the country) would lead to the need for additional annual purchases by Ukraine of 4.7 million tons of coal for thermal power plants and thermal power plants, table. 4.2, which would also have a negative impact on the environment. Such costs (decommissioning of the Chernobyl nuclear power plant and future losses from unfinished units at other nuclear power plants) were impossible for Ukraine.

Table 2 – Comparison of the operation of thermal power plants and nuclear power plants with a capacity of 1000 MW when they operate throughout the year

Therefore, just three years later, in 1993, the Supreme Council of Ukraine lifted the moratorium on the construction of nuclear power plant units. Work continued on the launch of the 6th unit of the Zaporozhye NPP (ZNPP), the 4th unit of the Rivne NPP (RNPP) and the 2nd unit of the Khmelnytsky NPP (KhNPP) in accordance with the start-up programs.

In the world energy industry, there are several types of power plants using nuclear fuel: NPP (nuclear power plants that supply electricity to consumers), ATEC (nuclear thermal power plants - nuclear plants that supply consumers not only with electricity, but also with heat), AST (nuclear heat supply plants are used for hot water supply) , ASPT (nuclear industrial heat supply stations are used to supply industrial enterprises with process steam). In Ukraine, only nuclear power plants operate, which provide nearby residential areas not only with electricity, but also with residual heat.

In table Table 3 provides data on the currently installed 15 double-circuit NPP units on the territory of Ukraine.

Table 3 – Power units nuclear power plants Ukraine with VVER type reactors

The nuclear energy industry in Russia is more diverse: by 2018, 10 operating nuclear power plants in Russia operated 37 power units with a total capacity of 30.214 GW, of which:

• 20 pressurized water reactors – 13 VVER-1000 (11 units of 1000 MW and 2 units of 1100 MW), 2 VVER-1200 (1200 MW), 5 reactors VVER-440 (4 units of 440 MW and 1 unit of 417 MW);
• 15 channel boiling water reactors – 11 RBMK-1000 (1000 MW each) and 4 EGP-6 (12 MW each);
• 2 fast neutron reactors – BN-600 (600 MW) and BN-800 (880 MW).

In the world, active construction of nuclear power plants began in the 70s of the twentieth century. By 1975, the total installed capacity of TG at nuclear power plants was 76 GW, in 1985 - 248.6 GW, in 2000 - 505 GW. By 2017, 193 nuclear power plants with 454 power units with a total capacity of about 391.8 GW were operating in 32 countries around the world. The world's most powerful power unit operates at the Civo NPP (France) with a capacity of 1561 MW: units No. 1 (1997) and No. 2 (1999), VVER-type reactors. On June 29, 2018, the first power unit of the Taishan NPP (China) with a capacity of 1,750 MW was launched; when it reaches full power, it will become the most powerful power unit in the world.

The world's largest nuclear power plant, the Kashiwazaki-Kariwa NPP (Japan), has 7 units with a boiling water-water single-circuit reactor BWR (RBMK) with a total capacity of 8212 MW, which were launched from 1985 to 1996. On December 22, 2018, the 4th power unit of the Tian Wan NPP (China) was connected to the network, and the installed capacity of all operating industrial nuclear reactors exceeded 500 GW. There are 54 power units under construction around the world. 169 are already closed. At the same time, old, low-power units are being shut down at nuclear power plants. Thus, in December 2018, French President E. Macron announced that by 2035 France would close 14 industrial nuclear reactors (out of 58 operating) with a total capacity of 900 MW.

The pace of development of nuclear energy is determined by specific conditions and reserves of organic fuel. In countries supplied with fossil fuels, at first the increase in nuclear power plant capacity proceeded at a slower pace, but as nuclear power plants were improved and their efficiency increased, the speed of construction increased. 50 years of experience in operating nuclear power plants around the world has shown that they can be economical (on average, electricity generated at a nuclear power plant is 2 times cheaper than “coal” thermal power plants), and, oddly enough, nuclear power plants are environmentally cleaner. But this same experience shows that if the rules of operation of stations are violated, leakage of radioactive media is possible, as was the case in the USA (nuclear power plants " Three Mile Island"), Germany, Great Britain, in Ukraine (Chernobyl NPP), in Japan (Fukushima-1), table. 4.4.

A nuclear power plant differs from thermal power plants in that the boiler is replaced by a nuclear reactor, in which nuclear fission energy is transferred to the primary circuit water, i.e. nuclear reaction is a source of primary thermal energy. In a steam generator, thermal energy is converted into kinetic energy of steam, which is then converted into mechanical energy of rotation of the turbine and rotor of the steam generator.

A double-circuit nuclear reactor is a vertical cylinder with an elliptical bottom, inside of which there is an active zone (fuel assemblies (FA)) and internal devices, Fig. 6. The top of the reactor is closed with a sealed lid, on which the electromagnetic drives of the mechanisms of the reactor control and protection organs are located, as well as connections for the cable output of the in-reactor control sensors. In the upper part of the housing there are eight pipes in two rows for supplying and discharging coolant, two for each of the 4 loops: four pipes for emergency supply of coolant in case of depressurization of the primary circuit and one pipe for control and measuring instruments (instrumentation). Water from the 1st circuit, after transferring heat to the 2nd circuit, returns to the reactor through the lower row of pressure pipes.

Table 4 – Data on some accidents at nuclear power plants around the world

a b

Figure 6 – NPP core: a – VVER-1000 reactor (dimensions in mm); b – General view of the main building of the nuclear power plant with the VVER-1000 reactor; c – fuel assembly loaded with fuel rods; d – reactor cover

1 – drives of the control and protection system; 2 – reactor cover; 3 – reactor vessel; 4 – block of protective pipes, inlet and outlet pipes; 5 – shaft; 6 – core partition; 7 – FA and control rods; 8 – reactor; 9 – turbogenerator

A solid annular partition between the rows of lower and upper nozzles separates the reactor vessel from the internal shaft and forms the downward movement of the coolant flow. Water passes down the annular gap, then through the perforated elliptical bottom and the support pipes of the shaft it enters the core, where the fuel rods assembled into fuel assemblies are located. The assemblies are lowered into the active zone. Structurally, fuel assemblies are long hexagons (about 4.0 m), in which 16 fuel rods are assembled, where tablets of compressed uranium oxide are located in sealed zirconium tubes, Fig. 7, A. Typically, a fuel assembly, in addition to uranium tubes, includes a tube with gadolinium, which traps fragments of radioactive elements resulting from the fission of uranium and extends the service life of fuel elements, Fig. 7, b.

Figure 7 – Reactor zone elements:a – non-activated “tablets” of compressed uranium oxide; b – a cover that covers the fuel assembly before loading into the reactor (the heads of the fuel elements are visible, in the center there is a tube with gadolinium)

A nuclear power plant can be single- or double-circuit (number of circuits in the reactor):

1. in single-circuit reactors, the coolant (water) from the reactor immediately goes to the steam generator, where it turns into steam, which goes to the turbine. This is how the RBMK reactors are designed, which were installed at the units of the Chernobyl Nuclear Power Plant (ChNPP) and at Fukushima-1. Currently, such reactors operate at the Kursk, Leningrad and Smolensk nuclear power plants. At the units that were started up after the Chernobyl accident, RBMK reactors were no longer installed. And only at the Smolensk NPP there is a unit (unit No. 3) with an RBMK reactor, which was put into operation in 1990, i.e. after the Chernobyl accident;
2. in double-circuit reactors (VVER type), the coolant of the 1st circuit receives heat in the reactor core and transfers it to the coolant of the 2nd circuit in the heat exchanger. In the steam generator, the heated water of the secondary circuit is converted into steam and supplied to the turbine. Technological diagrams of NPP power units with single- and double-circuit reactors are shown in Fig. 8.

Figure 8 – Technological diagram: a – single-circuit power unit; b – double-circuit power unit of a nuclear power plant CPS – reactor control and protection system; reactor control and protection system; ECCS - emergency cooling system of the reactor zone

The reactor is mounted in a steel casing designed for high pressure (up to 1.6·107 Pa or 160 atmospheres). The first, radioactive, circuit of the VVER reactor consists of a reactor and four circulation cooling loops. The coolant circulates through the 1st circuit - non-boiling water under a pressure of about 16 MPa with the addition of a solution boric acid(strong neutron absorber) to regulate reactor power. The coolant enters the reactor at a temperature of about +289 °C and is heated in it to +322 °C.

Then it is sent through 4 circulation loops to the steam generator (“hot” threads), where it transfers its heat to the coolant of the 2nd circuit. From the steam generators, water is returned to the reactor (“cold” lines) by the main circulation pumps (MCP). To maintain pressure and compensate for changes in the volume of the coolant when it warms up or cools down, a pressure compensator (volume compensator) is used, connected to one of the “hot” threads. Boiling water of the 2nd circuit is converted into saturated steam with a temperature of 280 °C and a pressure of 6.4 MPa, which enters the turbine through collecting steam lines.

The second circuit, non-radioactive, includes a steam generator, water supply unit and one turbine unit. To control processes and to protect a nuclear reactor, control rods (filled mainly with boron carbide) are used, which are moved along the height of the active zone. When the rods are inserted deeply, the chain reaction stops. The rods are moved remotely from the control panel. With slight movement of the rods, the chain reaction develops or dies out. This is how the power of the reactor is regulated.

The efficiency of using nuclear fuel at nuclear power plants with thermal neutron reactors is characterized by the average annual energy production per 1 ton (or per 1 kg) of fuel loaded and spent in the reactor and its average burnup (MW day/t). 163 fuel assemblies with weakly enriched uranium U-235 are loaded into the nuclear power plant reactor, and 312 fuel rods are installed in each fuel assembly. The fuel weight of one fuel assembly is 571 kg. Total weight loading of nuclear fuel into the reactor - about 93 tons.

In the technological cycle of any nuclear power plant, a cooling system for the spent coolant (water) is provided in order to bring the temperature of the coolant to the value required for the repeated cycle. If there is a populated area near the power plant, then the heat from the waste coolant is used for heating houses and hot water supply, and if not or the discharge is insufficient, then the excess heat is discharged into the atmosphere in cooling towers, in cooling pools, in channels with pipes - sprinklers, Fig. 9.

Figure 9 – Cooling systems for spent coolant (water) at nuclear power plants:a – cooling towers of the Rivne NPP; b – industrial site of Zaporizhia NPP with cooling pools; c – spray pool of Khmelnitsky NPP

One of the main problems of nuclear power plants in the world is the issue of storing spent nuclear fuel (SNF), the creation of permanent, long-term storage facilities. They should completely ensure the storage of spent nuclear fuel for several thousand years, because Only during this time will the fuel lose its residual radioactivity. Currently, not a single state in the world has a full-fledged permanent storage facility, although work on their creation is ongoing.

The USSR provided for the removal of spent fuel (after 1.5–2 years of storage in the primary cooling pools in the “dirty zone” of the unit) to a stationary storage facility in Russia. However, it soon became clear that due to the limited capabilities of the storage facility, the lack of the possibility of its expansion, as well as the impossibility of reprocessing spent fuel directly after its delivery from nuclear power plant units, problems would arise with the nuclear power industry in meeting the requirement to ensure safe operation.

Therefore, since 1991, the search began for new methods of storing spent fuel for all nuclear power plants in Ukraine, and, first of all, for the largest nuclear power plant in Ukraine - Zaporizhia NPP. According to experts, at this station, due to a shortage of free cells in the primary storage pools, all units would have to be shut down by 1998, and half of the enterprises and population of Ukraine would have to be left without electricity. In agreement with the State Committee for Atomic Energy of Ukraine, ZNPP announced an international competition for best project storage facilities for spent nuclear fuel.

After careful analysis, a project based on dry ventilated container storage technology, proposed by the companies " Sierra NewClear Corporation" And " Duke Engineering and Services» ( DE&S). Company technology DE&S was recognized as the most environmentally safe, practical, efficient, cost-effective and best suited to the specific needs of Zaporizhia NPP. Company project DE&S was licensed by the US regulatory authorities and by the time it was selected for ZNPP, it had already been implemented at two US NPPs. When choosing, we took into account the possibility of manufacturing containers for dry storage of spent nuclear fuel (DSF) at Ukrainian enterprises from domestic materials (for example, in the city of Energodar). The type of storage facility was approved by the decision of the Scientific and Technical Council of the State Committee for Atomic Energy on January 12, 1995.

The selected option (DFS) uses the technology of storing fuel assemblies in a vertical position in ventilated concrete containers. Containers provide dry, sealed and safe storage of fuel assemblies. Each DSF container is designed for the safe storage of 380 fuel assemblies (9000 fuel rods) from pressurized water reactor plants VVER-1000. The system is passive and, after installing concrete containers on the storage site, does not require significant maintenance, except for monitoring the helium content ( Not) near the spent fuel storage containers: the volume of the containers, before the final sealing of the lid, is filled with helium gas to control its tightness. The service life of a DSF container is 30 years, after which reloading into a new container is required.

The spent fuel storage facility consists of three main parts, Fig. 10, A: ventilated concrete container, storage basket, transfer container. The ventilated concrete container for dry fuel storage is designed for long-term intermediate storage of baskets with spent nuclear fuel, providing their cooling and the necessary biological protection. Cooling is carried out by its own circulation of air around the steel walls of the basket, which passes through the cylindrical gap between the outer surface of the basket and the inner surface of the concrete container. Ventilated concrete DSF containers are moved by special conveyors to a concrete site located within the territory of the nuclear power plant, Fig. 10, b.

Figure 10 – DSF container and its transportation:Ab

1 – temperature control sensor; 2 – air inlet and guides for transportation; 3 – concrete storage area; 4 – air outlet; 5 – concrete container lid; 6 – power and protective covers of the basket; 7 – block of 24 guide tubes for fuel assemblies; 8 – guide tube; 9 – body of a multi-place storage basket; 10 – shell; 11 – ventilated concrete container

The storage basket is a hermetically sealed container designed to accommodate 24 fuel assemblies from a VVER-1000 reactor in a DSF transfer container. A transfer container is a container designed for temporary placement and transportation of a loaded basket from the storage pool to the DSF container. The main purpose of the transfer container is to protect NPP personnel from radiation exposure when performing transport and technological operations with the basket. The container is made of welded metal structures and concrete. In table Figure 5 shows the design parameters of the DSF transfer container.

Table 5 – Parameters of the DSF transfer container

To ensure spent fuel storage, NPP equipment, sites and systems are used: repair shops; equipment for storage and transportation areas; decontamination systems, power supply and communications, ventilation and air conditioning; fire extinguishing system. In Fig. 11 shows a plan for the placement of buildings and equipment of the Zaporizhzhya NPP. However dry storage was not introduced at all Ukrainian nuclear power plants, only at Zaporizhia NPP. SNF from other nuclear power plants is transported to Russian storage facilities. Since 2005, Ukraine has paid Russia $2 billion for storing spent fuel from domestic nuclear power plants.

Creating your own nuclear waste storage facility (ISF) is 2.5 times cheaper than transferring it for storage to Russia. Therefore, work on creating new types of own storage facilities continued continuously, and it was proposed to create a new storage facility on the territory of the Chernobyl Nuclear Power Plant. Currently, work on creating a Ukrainian storage facility is coming to an end. Operation of the new ISF on the territory of the Chernobyl Nuclear Power Plant (ISF-2) at full capacity should begin at the end of 2019. Over the course of 9.5 years, it is planned to move spent fuel from all units of Ukrainian nuclear power plants (South Ukraine NPP, Rivne NPP and KhNPP) to ISF-2, where it will be stored for another 100 years.

Figure 11 –

1. Reactor compartment
2. Turbine department
3. Diesel generator
4. Block pumping station
5. Special Corps 1 and 2
6. Solid waste storage
7. Auxiliary building
8. Laboratory and utility buildings
9. Administrative building
10. Checkpoint 2
11. Disposal site
12. Splash Pools
13. Checkpoint 1
14. Full scale simulator
15. Educational and training center

At ISF-2, spent fuel will be stored using dry modular storage technology, in which fuel will be stored in sealed baskets filled with inert gas. Experts believe that it is better to store spent fuel for a long time not in an aqueous environment, but in a gas environment. The baskets will be placed in concrete modules, the design of the module serves as radiation protection and also prevents damage to the metal basket. From the nuclear power plant site in a special sealed container car, spent fuel is transferred to concrete storage modules, Fig. 12.

Figure 12 – Sealed container car for transportation of spent nuclear fuel

Reloading of fuel assemblies from the primary cooling pool of the reactor zone into a container car is carried out using special device, which allows you to move the container to a vertical position, load the contents from the hot chamber, return it to a horizontal position and transport it to a storage location.

The technology adopted for ISF-2 involves the use of a double-walled dry shielded canister (DSEP), Fig. 13. Its design ensures long-term storage by isolating it from the environment. Accordingly, there will be no radiation impact on the environment during normal storage in concrete modules.

One DSEP contains 93 spent fuel assemblies.

At thermal power plants, the chemical energy of the burned fuel is converted in the boiler into the energy of water steam, which drives a turbine unit (steam turbine connected to a generator). The mechanical energy of rotation is converted by the generator into electrical energy. The fuel for power plants is coal, peat, oil shale, as well as gas and fuel oil. In the domestic energy sector, CPPs account for up to 60% of electricity generation.

The main features of IES are: remoteness from electricity consumers, which mainly determines the output of power at high and ultra-high voltages, and the block principle of constructing a power plant. The power of modern CPPs is usually such that each of them can provide electricity to a large region of the country. Hence, another name for power plants of this type is the state district power station (GRES).

Fig.1. General view of a modern IES
1 - main building, 2 - auxiliary building,
3 - open distribution device, 4 - fuel storage

Fig.2. Fundamental technological scheme IES
1 - fuel storage and fuel supply system,
2 - fuel preparation system, 3 - boiler,
4 - turbine, 5 - condenser, 6 - circulation pump,
7 - condensate pump, 8 - feed pump,
9 - boiler burners, 10 - fan, 11 - smoke exhauster,
12 - air heater, 13 - water economizer,
14 - low pressure heater, 15 - deaerator,
16 - high pressure heater.

Figure 1 shows a general view of a modern IES, and Figure 2 shows a simplified schematic diagram of a IES power unit. The power unit is like a separate power plant with its own main and auxiliary equipment and a control center - a block board. Connections between neighboring power units along technological lines are usually not provided. Construction of IES on a block principle provides certain technical and economic advantages, which are as follows:

• the use of steam with high and ultra-high parameters is facilitated due to a simpler steam pipeline system, which is especially important for the development of high-power units;
• the technological diagram of the power plant is simplified and becomes clearer, as a result of which the reliability of operation increases and operation becomes easier;
• decreases, and in in some cases There may be no backup thermal-mechanical equipment at all;
• the volume of construction and installation work is reduced; capital costs for the construction of a power plant are reduced;
• convenient expansion of the power plant is ensured, and new power units, if necessary, can differ from the previous ones in their parameters.

The IES technological scheme consists of several systems: fuel supply; fuel preparation; main steam-water circuit together with a steam generator and turbine; circulating water supply; water treatment; ash collection and ash removal and, finally, the electrical part of the station (Fig. 2).

The mechanisms and installations that ensure the normal functioning of all these elements are included in the so-called auxiliary system of the station (power unit).

The greatest energy losses at IES occur in the main steam-water circuit, namely in the condenser, where the exhaust steam, which still contains a large amount of heat expended during steam formation, gives it back to the circulating water. Heat is carried away with circulating water into reservoirs, i.e. gets lost. These losses mainly determine the efficiency of the power plant, which is no more than 40-42% even for the most modern CPPs.

The electricity generated by the power plant is supplied at a voltage of 110-750 kV and only part of it is selected for its own needs through an own needs transformer connected to the generator terminals.

Generators and step-up transformers are combined into power units and connected to a high voltage switchgear, which is usually an open switchgear (OSG). Options for the location of the main structures can be different, as illustrated in Fig. 3.

Rice. 3. Options for the location of the main IES facilities
1 - main building; 2 - fuel storage;
3 - chimneys; 4 - block transformers;
5,6 - distribution devices; 7 - pumping stations;
8 - intermediate supports of electrical lines

Modern CPPs are mainly equipped with power units of 200-800 MW. The use of large units makes it possible to ensure a rapid increase in the capacity of power plants, acceptable cost of electricity and the cost of an installed kilowatt of plant power.

The largest CPPs currently have a capacity of up to 4 million kW. Power plants with a capacity of 4-6.4 million kW with power units of 500 and 800 MW are being built. The maximum power of a IES is determined by the water supply conditions and the impact of plant emissions on the environment.

Modern CESs have a very active impact on the environment: the atmosphere, hydrosphere and lithosphere. The impact on the atmosphere is reflected in the large consumption of air oxygen for fuel combustion and the emission of a significant amount of combustion products. These are primarily gaseous oxides of carbon, sulfur, and nitrogen, some of which have high chemical activity. Fly ash passing through ash collectors pollutes the air. The least air pollution (for stations of the same power) is observed when burning gas and the greatest - when burning solid fuel with low calorific value and high ash content. It is also necessary to take into account the large loss of heat into the atmosphere, as well as the electromagnetic fields created by electrical installations of high and ultra-high voltage.

IES pollutes the hydrosphere with large masses of warm water discharged from turbine condensers, as well as industrial wastewater, although they undergo thorough purification.

For the lithosphere, the influence of CES is reflected not only in the fact that for the operation of the station large masses of fuel are extracted, land is alienated and built up, but also in the fact that a lot of space is required for the burial of large masses of ash and slag (when burning solid fuels).

The impact of IES on the environment is extremely large. For example, the scale of thermal pollution of water and air can be judged by the fact that about 60% of the heat that is obtained in the boiler when the entire mass of fuel is burned is lost outside the station. Considering the size of electricity production at CPPs and the volumes of fuel burned, it can be assumed that they are able to influence the climate of large areas of the country. At the same time, the problem of recycling part of the thermal emissions is being solved by heating greenhouses and creating heated fish ponds. Ash and slag are used in the production of building materials, etc.

Cogeneration power plants - combined heat and power plants (CHP)

This type of power plant is intended for centralized supply of electricity and heat to industrial enterprises and cities. Being, like IES, thermal power plants, they differ from the latter in the use of heat from steam “spent” in turbines for the needs of industrial production, as well as for heating, air conditioning and hot water supply. With such combined generation of electricity and heat, significant fuel savings are achieved compared to separate energy supply, i.e. generating electricity at CPPs and receiving heat from local boiler houses. Therefore, thermal power plants have become widespread in areas (cities) with high consumption of heat and electricity. In general, thermal power plants produce about 25% of all electricity generated in Russia.

Fig.4. Features of the technological scheme of the thermal power plant
1 - network pump; 2 - network heater

Features of the technological scheme of the thermal power plant are shown in Fig. 4. Parts of the circuit that are similar in structure to those for IES are not indicated here. The main difference lies in the specifics of the steam-water circuit and the method of generating electricity.

The specifics of the electrical part of a thermal power plant are determined by the location of the power plant near the centers of electrical loads. Under these conditions, part of the power can be supplied to the local network directly at the generator voltage. For this purpose, a generator switchgear (GRU) is usually created at a power plant. Excess power is supplied, as in the case of IES, into the power system at increased voltage.

An essential feature of thermal power plants is also increased power thermal equipment compared to the electrical output of the power plant. This circumstance predetermines a higher relative consumption of electricity for own needs than for IES.

The location of thermal power plants mainly in large industrial centers and the increased power of thermal equipment compared to electrical equipment increase the requirements for environmental protection. Thus, to reduce emissions from thermal power plants, it is advisable, where possible, to use primarily gaseous or liquid fuels, as well as high-quality coals.

The placement of the main equipment of stations of this type, especially for block-type thermal power plants, corresponds to that for CPPs. Only those stations that provide for a large supply of electricity from the generator switchgear to the local consumer have special features. In this case, a special building is provided for the GRU, located along the wall of the machine room (Fig. 5).

Fig.5. Option for placement of main equipment
on the site of a thermal power plant with a separate GRU building
1 - chimneys; 2 - main building; 3 - multi-ampere conductors;
4 - GRU building; 5 - communication transformer; 6 - outdoor switchgear;
7 - cooling towers (fuel storage for thermal power plants is not shown)

Nuclear power plants (NPP)

Nuclear power plants are essentially thermal power plants that use the thermal energy of nuclear reactions.

One of the main elements of a nuclear power plant is the reactor. In Russia, as in many countries of the world, they mainly use nuclear reactions of fission of uranium U-235 under the influence of thermal neutrons. To implement them, in addition to fuel (U-235), the reactor must have a neutron moderator and, of course, a coolant that removes heat from the reactor. In VVER (water-water energy) reactors, ordinary water under pressure is used as a moderator and coolant. In reactors of the RBMK type (high-power channel reactor), water is used as a coolant, and graphite is used as a moderator. Both of these reactors are widely used at nuclear power plants in Russia.

Fig.6. Schematic flow diagram of a nuclear power plant with a VVER-type reactor
1 - reactor; 2 - steam generator;
3 - turbine; 4 - generator;

7 - condensate (feed) pump;
8 - main circulation pump

NPP circuits in the thermal part can be implemented in various versions. Figure 6 shows, as an example, a double-circuit diagram of a nuclear power plant for power plants with VVER reactors. It can be seen that this scheme is close to the IES scheme, however, instead of a steam generator using organic fuel, a nuclear installation is used here.

NPPs, as well as IESs, are built according to the block principle in both the thermomechanical and electrical parts.

Nuclear fuel, the reserves of which are quite large, has a very high calorific value (1 kg of U-235 replaces 2900 tons of coal), so nuclear power plants are especially effective in areas poor in fuel resources, for example, in the European part of Russia.

It is advantageous to equip nuclear power plants with high-power power units. Then, in terms of their technical and economic indicators, they are not inferior to IES, and in some cases even surpass them. Currently, reactors with an electrical power of 440 and 1000 MW of the VVER type, as well as 1000 and 1500 MW of the RBMK type have been developed. In this case, the power units are formed as follows: the reactor is combined with two turbine units (VVER-440 reactor and two 220 MW turbo units, a 1000 MW reactor and two 500 MW turbo units, an RBMK-1500 reactor and two 750 MW turbo units), or the reactor is combined with turbine unit of the same power (1000 MW reactor and 1000 MW unit power turbine unit).

Fig.7. Schematic flow diagram of a nuclear power plant with a BN type reactor
a - the principle of the reactor core;
b - technological diagram:
1 - reactor; 2 - steam generator; 3 - turbine; 4 - generator;
5 - transformer; 6 - turbine condenser;
7 - condensate (feed) pump; 8 - heat exchanger of sodium circuits;
9 - non-radioactive sodium pump; 10 - radioactive sodium pump

Nuclear power plants with fast neutron reactors (BN), which can be used to generate heat and electricity, as well as to reproduce nuclear fuel, are promising. The technological diagram of the power unit of such a nuclear power plant is presented in Fig. 7. A BN-type reactor has an active zone where a nuclear reaction occurs, releasing a stream of fast neutrons. These neutrons act on elements from U-238, which is not usually used in nuclear reactions, and transform it into plutonium Pn-239, which can subsequently be used in nuclear power plants as nuclear fuel. The heat from the nuclear reaction is removed by liquid sodium and used to generate electricity.

The design of a nuclear power plant with a BN reactor is three-circuit, two of them use liquid sodium (in the reactor circuit and in the intermediate circuit). Liquid sodium reacts violently with water and steam. Therefore, in order to avoid contact of radioactive sodium of the primary circuit with water or water vapor in case of accidents, a second (intermediate) circuit is performed in which the coolant is non-radioactive sodium. The working fluid of the third circuit is water and water vapor.

Currently, a number of BN-type power units are in operation, of which the largest is BN-600.

Nuclear power plants do not have flue gas emissions and do not have waste in the form of ash and slag. However, the specific heat release into the cooling water of nuclear power plants is greater than that of thermal power plants, due to the higher specific steam consumption and, consequently, the higher specific cooling water consumption. Therefore, most new nuclear power plants provide for the installation of cooling towers, in which heat from the cooling water is removed to the atmosphere.

An important feature of the possible impact of nuclear power plants on the environment is the need for disposal of radioactive waste. This is done in special burial grounds, which exclude the possibility of radiation exposure to people.

To avoid the influence of possible radioactive emissions from nuclear power plants on people during accidents, special measures have been taken to increase the reliability of equipment (duplication of safety systems, etc.), and a sanitary protection zone is created around the plant.

The possible placement of the main structures of a nuclear power plant using the example of a station with VVER-1000 units is shown in Fig. 8.

Fig.8. Option for placing the main components of nuclear power plants with VVER-1000 type reactors
1 - reactor room; 2 - machine room; 3 - transformer platform;
4 - discharge channel (closed); 5 - pumping station;
6 - water supply channel (open); 7 - outdoor switchgear; 8 - outdoor switchgear shield;
9 - combined auxiliary building; 10 - diesel-electric station;
11 - special water treatment building; 12 - administrative and amenity complex

Hydroelectric power plants (HPP)

Hydroelectric power plants use the energy of water flows (rivers, waterfalls, etc.) to generate electricity. Currently, hydroelectric power plants produce about 15% of all electricity. More intensive construction of this type of stations is hampered by large capital investments, long construction periods and the specific distribution of hydro resources throughout Russia (most of them are concentrated in the eastern part of the country).

Currently water resources are used mainly through the construction of powerful hydroelectric power plants, such as the Krasnoyarsk hydroelectric power station (6 million kW), the Bratsk hydroelectric power station (4.5 million kW), the Sayano-Shushenskaya hydroelectric power station (6.4 million kW), the Ust-Ilimsk hydroelectric power station (4, 32 million kW), etc.

The primary engines at hydroelectric power plants are hydraulic turbines, which drive synchronous hydrogenerators. The power developed by the hydraulic unit is proportional to the pressure H and water flow Q, i.e.

Thus, the power of a hydroelectric power station is determined by the flow and pressure of water.

Fig.9. Schematic flow diagram of a hydroelectric power station

At a hydroelectric power station, as a rule, the water pressure is created by a dam (Fig. 9). The water area in front of the dam is called the upstream, and below the dam is called the downstream. The difference between the levels of the upper (UWB) and lower pool (UNB) determines the pressure N.

The headwaters form a reservoir in which water is stored and used as needed to generate electricity.

The hydroelectric complex on a flat river includes: a dam, a power plant building, spillways, navigation gates (locks), fish passage structures, etc.

On mountain rivers Hydroelectric power stations are being built that take advantage of the large natural slopes of the river. However, in this case it is usually necessary to create a system of diversion structures. These include structures that direct water bypassing the natural river bed, diversion channels, tunnels, and pipes.

In the electrical part, hydroelectric power plants are in many ways similar to condensing power plants. Like CPPs, hydroelectric power plants are usually located far from consumption centers, since the location of their construction is determined mainly by natural conditions. Therefore, the electricity generated by hydroelectric power plants is supplied at high and ultra-high voltages (110-500 kV). A distinctive feature of hydroelectric power plants is the low consumption of electricity for their own needs, which is usually several times less than at thermal power plants. This is explained by the absence of large mechanisms in the system of auxiliary needs at hydroelectric power stations.

During the construction of hydroelectric power stations, important national economic problems are solved simultaneously with energy ones: land irrigation and the development of navigation, ensuring water supply to large cities and industrial enterprises, etc.

The technology for generating electricity at hydroelectric power plants is quite simple and easy to automate. Starting up a hydroelectric power plant unit takes no more than 50 seconds, so it is advisable to provide power reserves in the power system with these units.

The efficiency of hydroelectric power plants is usually about 85-90%.

Due to lower operating costs, the cost of electricity at hydroelectric power plants is usually several times lower than at thermal power plants.

Fig. 10. Scheme of pumped storage power plant

Pumped storage power plants (PSPPs) play a special role in modern energy systems. These power plants have at least two basins - upper and lower with certain elevation differences between them (Fig. 10). So-called reversible hydraulic units are installed in the pumped storage power plant building. During the hours of minimum load on the power system, pumped storage power plant generators are switched to motor mode, and turbines are switched to pumping mode. Consuming power from the network, such hydraulic units pump water through a pipeline from the lower basin to the upper one. During the period of maximum loads, when there is a shortage of generating capacity in the energy system, the pumped storage power plant generates electricity. Using water from the upper pool, the turbine rotates the generator, which supplies power to the network.

Thus, the use of pumped storage power plants helps to level out the load schedule of the energy system, which increases the efficiency of operation of thermal and nuclear power plants.

The impact of hydroelectric power plants and pumped storage power plants on the environment is associated with the construction of dams and reservoirs. This circumstance, in addition to alienation large areas lands with their natural resources, affects changes in the landscape, groundwater levels, reshaping of banks, increased evaporation of water, etc. During the construction of large hydroelectric reservoirs, in addition, conditions are created for the development of tectonic activity.

The location of the main facilities included in the power plants is shown using the example of a hydroelectric power station near a dam (Fig. 11).

Rice. 11. Location of the main facilities of the dam hydroelectric power station
a - plan:
1 - hydroelectric power station building; 2 - station concrete dam; 3 - concrete spillway;
4 - right- and left-bank rockfill dams; 5 - outdoor switchgear of HV and EHV;
b - section along the station dam:
1 - dam; 2 - water conduit;
3 - site for high voltage electrical equipment;
4 - HPP turbine room building

Gas turbine power plants

The basis of modern gas turbine power plants are gas turbines with a capacity of 25-100 MW. A simplified schematic diagram of the power unit of a gas turbine power plant is shown in Fig. 12.

Fig. 12. Schematic diagram of a power plant with gas turbines
KS - combustion chamber; KP - compressor; GT - gas turbine;
G - generator; T - transformer; M - starting motor

Fuel (gas, diesel fuel) is supplied to the combustion chamber, and compressed air is pumped into it by a compressor. Hot combustion products give off their energy to a gas turbine, which rotates a compressor and a synchronous generator. The installation is started using an accelerating engine and lasts 1-2 minutes, and therefore gas turbine units (GTUs) are highly maneuverable and suitable for covering load peaks in power systems. The main part of the heat obtained in the combustion chamber of a gas turbine plant is released into the atmosphere, so the overall efficiency of such power plants is 25-30%.

To increase the efficiency of gas turbines, combined cycle gas units (CCGs) have been developed. In them, fuel is burned in the furnace of a steam generator, the steam from which is sent to the steam turbine. The combustion products from the steam generator, after they have been cooled to the required temperature, are sent to the gas turbine. Thus, the CCGT has two electric generators driven into rotation: one by a gas turbine, the other by a steam turbine.

Unconventional types of power plants

These are primarily power plants with magnetohydrodynamic generators (MHD generators). MHD generators are planned to be built as an add-on to a IES type station. They use thermal potentials of 2500-3000 K, unavailable to conventional boilers.

Fig. 13. Schematic diagram of IES with MHD generator
1 - combustion chamber; 2 - MHD channel; 3 - magnetic system;
4 - air heater; 5 - steam generator (boiler); 6 - steam turbines;
7 - compressor; 8 - condensate (feed) pump

A schematic diagram of a thermal power plant with an MHD installation is shown in Fig. 13. Gaseous products of fuel combustion, into which an easily ionizable additive (for example, K 2 CO 3) is introduced, are directed into an MHD channel penetrated by a high-intensity magnetic field. The kinetic energy of ionized gases in the channel is converted into direct current electrical energy, which, in turn, is converted into three-phase alternating current and sent to the power system to consumers.

The exhaust of the MHD channel at a temperature of about 2000 K is sent to the boiler and is used according to the usual scheme for steam generation using steam energy in the steam turbine of the thermal power plant.

For many years now, in many advanced and technically developed countries around the world, work is underway to harness the energy of thermonuclear fusion. The essence of a thermonuclear reaction, in which a colossal amount of energy can be released, is the fusion of two atoms (ions) of light elements (usually ions of hydrogen isotopes - deuterium and tritium or hydrogen and deuterium). As a result, a particle is formed with a mass less than the total mass of the initial elements, and the released energy corresponds to the mass difference.

The reaction can be carried out under very specific conditions: the temperature of the starting substance should be about 10 8 K, i.e. it is in a state of high-temperature plasma; plasma pressure several hundred megapascals; its holding time is at least 1s. When using reaction energy for industrial purposes, these conditions must be created cyclically. It is extremely difficult to implement these requirements. Currently, two main ways to achieve this goal are visible: plasma confinement by a powerful static magnetic field or inertial confinement, in which fuel in the form of small portions is heated and compressed by concentrated laser beams or electron beams.

Rice. 14. Schematic diagram of a thermonuclear power plant based on a Tokamak-type reactor
1 - deuterium-tritium plasma; 2 - vacuum space;
3 - superconducting magnet; 4 - blanket;
5 - primary circuit heat exchanger; 6 - secondary circuit heat exchanger;
7 - plasma heating transformer

The former USSR was one of the leaders in the development of methods for magnetic plasma confinement in Tokamak-type installations. A prototype of a thermonuclear power plant based on a reactor of this type is shown in Fig. 14. The basis of the reactor and power plant unit is a toroidal chamber, along the axis of which plasma 1 is concentrated in vacuum 2, where the thermonuclear reaction occurs. Plasma is contained by a powerful superconducting magnet 3, and heated by a transformer 7.

The reaction of deuterium + tritium is considered. While deuterium can be isolated from natural water, tritium is produced artificially, which requires a lot of energy and labor. To reproduce the tritium that is consumed during the reaction, a blanket of lithium 4 is constructed in the reactor chamber. Lithium irradiated with neutrons during the reaction partially forms helium and tritium, which can be separated from the lithium and returned to the reactor. This way its reproduction can be carried out.

The lithium blanket performs another function - it transfers the heat generated during thermonuclear fusion. Being in a liquid state, it circulates through heat exchanger 5 and transfers heat to an intermediate liquid metal coolant (for example, potassium), which, in turn, heats the water in the next heat exchanger 6, which operates like a steam boiler at a thermal power plant or a steam generator at a nuclear power plant. The considered diagram gives only a very simplified idea of ​​one possible way creating a station of this type.

The creation of a thermonuclear power plant raises a number of serious theoretical and practical problems that require complex research, and therefore the final mastery of thermonuclear fusion is a matter, perhaps not so distant, but still of the future. Experience shows that this is one of the most difficult technological tasks that humanity has ever undertaken. However, if successful, a virtually limitless amount of energy will be provided.

Along with the search for new powerful energy sources, the development and construction of stations using renewable energy resources of an environmentally “clean” type, the impact of which on the environment is minimal, is underway. These are stations that use the energy of the sun, wind, tides, etc.

The sun's energy can be harnessed through photovoltaic cells by directly generating electricity, or by using thermal radiation from the sun focused by mirrors on a steam generator, the steam from which rotates a turbine with a generator. The first type of solar stations is still used to a limited extent and only in special installations, but as the cost decreases and the efficiency of photocells increases, it will become possible to widely use them in large-scale energy production. The second type of solar station is easier to implement. Thus, a pilot industrial station with a capacity of 5 MW was built in the USSR.

Wind power plants (WPPs) in Russia have not yet become widespread to meet the needs of energy systems. They are used for relatively small autonomous consumers. However, studies on powerful power plants of this type, carried out in Russia (up to several tens of megawatts per unit) and abroad (up to several megawatts per unit with a two-blade wind wheel diameter of up to 100 m), speak in favor of wind farms.

The advantages of tidal power plants can be judged by the fact of successful operation at tidal heights of up to 13 m of the Kislogubskaya TPP, built on the Kola Peninsula. A number of regions of Russia have been identified where it is possible and advisable to construct a power plant with a capacity of tens to hundreds of megawatts.

Geothermal power plants use the energy of underground thermal waters. There are areas in Russia where geothermal power plants can be built (Kamchatka, Caucasus, etc.). The performance of such stations has been proven by the experience of their operation in the USA, Italy, New Zealand, Mexico and other countries. The Pauzhetskaya Geothermal Power Plant is successfully operating in Kamchatka.

« Physics - 11th grade"

Electricity production

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

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 - TPP 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 turbogenerators are very fast: the rotor speed is several thousand per minute.

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

Thermal power plants - CHP allow a significant part of the waste steam energy to be used at industrial enterprises and for domestic needs.
As a result, the efficiency of the thermal power plant 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 - hydroelectric power station The potential energy of water is used to rotate the generator rotors.

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 usage

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 machinery in industry is driven by electric motors.

Electricity transmission

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

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

If the line length is very long, energy transmission may become economically unprofitable.
It is practically very difficult to significantly reduce the line resistance R, so it is necessary to reduce the current I.

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

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

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

This is achieved using step-down transformers.

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

If the voltage is very high, a discharge may begin between the wires, leading to energy loss.
The permissible amplitude of the alternating voltage must be such that for a given area cross section wire energy losses due to discharge were negligible.

Electric stations are connected by high-voltage power lines, forming a common electrical network to which consumers are connected.
This connection, called a power grid, makes it possible to distribute energy consumption loads.
The power system ensures uninterrupted supply of energy to consumers.
Now our country has a Unified Energy System for the European part of the country.

Electricity usage

The demand for electricity is constantly increasing both in industry, transport, scientific institutions, and in everyday life. There are two main ways to satisfy this need.

The first is the construction of new powerful power plants: thermal, hydraulic and nuclear.
However, building 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 technologies make 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 using controlled thermonuclear reactions.

Priority should be given to increasing energy efficiency rather than increasing power plant capacity.

Story [ | ]

The basic principle of generating electricity was discovered in the 1820s and early 1830s by British scientist Michael Faraday. His method, which is still used today, is that in a closed conductive circuit, when this circuit moves between the poles of a magnet, an electric current arises.

With the development of technology, the following scheme for generating electricity has become economically profitable. Electric generators installed in a power plant centrally produce electrical energy in the form of alternating current. With the help of power transformers, the electrical voltage of the generated alternating current is increased, which allows it to be transmitted through wires with low losses. At the point of consumption of electrical energy, the AC voltage is reduced using step-down transformers and transmitted to consumers. Electrification, along with the Bessemer method of steel smelting, became the basis of the Second Industrial Revolution. The main inventions that made electricity accessible and indispensable were made by Thomas Alva Edison and Nikola Tesla.

The production of electricity in central power plants began in 1882, when at the Pearl Street Station in New York City, a steam engine drove a dynamo that produced direct current to light Pearl Street. The new technology was quickly adopted by many cities around the world, which quickly converted their street lights to electric power. Soon after, electric lamps began to be widely used in public buildings, factories and to power public transport (trams and trains). Since then, the production of electrical energy in the world has been constantly increasing.

Electricity generation methods[ | ]

The main method of producing electrical energy is its generation by an electric generator, located on the same axis with the turbine, and converting the kinetic energy of rotation of the turbine into electricity. Depending on the type of working agent that rotates the turbine, power plants are divided into hydraulic and thermal (including nuclear).

Hydropower[ | ]

Hydropower is a branch of electricity production that uses the kinetic energy of water flow to produce electricity. Energy production enterprises in this area are hydroelectric power plants (HPPs), which are built on rivers.

When constructing a hydroelectric power station with the help of dams on rivers, a difference in water surface levels (upper and lower pools) is artificially created. Under the influence of gravity, water flows from the upper pool to the lower pool through special conduits in which water turbines are located, the blades of which are spun by the water flow. The turbine rotates the coaxial rotor of the electric generator.

A special type of hydroelectric power station is pumped storage power station (PSPP). They cannot be considered generating facilities in their pure form, since they consume almost as much electricity as they produce, but such stations are very effective in unloading the network during peak hours.

Thermal power engineering[ | ]

Thermal power industry enterprises are thermal power plants (TPPs), where the thermal energy of combustion of organic fuel is converted into electrical energy. Thermal power plants come in two main types:

Economics of Electricity Production[ | ]

The construction of electric power facilities is very expensive, and their payback period is long. The economic efficiency of a particular method of generating electricity depends on many parameters, primarily on the demand for electricity and the region. Depending on the ratio of these parameters, selling prices for electricity also vary; for example, the price of electricity in Venezuela is 3 cents per kWh, and in Denmark - 40 cents per kWh.

The choice of power plant type is also based primarily on local power needs and fluctuations in demand. In addition, all electrical networks have different loads, but power plants that are connected to the network and operate continuously must provide the base load - the daily minimum consumption. The base load can only be provided by large thermal and nuclear power plants, the power of which can be adjusted within certain limits. In hydroelectric power plants, the ability to regulate power is much less.

It is preferable to build thermal power plants in areas with high density industrial consumers. The negative impact of waste pollution can be minimized because power plants are usually located away from residential areas. The type of fuel burned is essential for a thermal power plant. Typically, the cheapest fuel for thermal power plants is coal. But if the price of natural gas falls below a certain limit, its use for generating electricity becomes preferable to generating electricity by burning coal.

The main advantage of nuclear power plants is the high power of each power unit at a relatively small sizes and high environmental friendliness with strict adherence to all operating rules. However, the potential dangers from the failure of nuclear power plants are very great.

Hydroelectric power plants are usually built in remote areas and are extremely environmentally friendly, but their output varies greatly depending on the time of year, and they cannot regulate the power supplied to the electrical grid within wide limits.

The cost of generating electricity from renewable sources (excluding hydropower) has fallen significantly recently. The cost of electricity produced from solar energy, wind energy, and tidal energy is in many cases already comparable to the cost of electricity produced from thermal power plants. Taking into account government subsidies, the construction of power plants operating with renewable sources is economically feasible. However, the main disadvantage of such power plants is the intermittent nature of their operation and the inability to regulate their power.

In 2018, generating electricity from offshore wind farms became cheaper than generating electricity from nuclear power plants.

Environmental issues[ | ]

Differences between electricity-producing countries influence environmental concerns. In France, only 10% of electricity is generated from fossil fuels, in the USA this figure reaches 70%, and in China - up to 80%. The environmental friendliness of electricity production depends on the type of power plant. Most scientists agree that pollutant and greenhouse gas emissions from fossil fuel-based electricity generation account for a significant portion of global greenhouse gas emissions; in the United States, electricity generation accounts for nearly 40% of emissions, the largest of any source. Transport emissions lag far behind, accounting for about a third of production