What type of raw materials is used in the operation of the power plant. Thermal power station device. How TPPs work on gas

Thermal power plants provide people with almost all the energy they need on the planet. People have learned to receive electricity in other ways, but still do not accept alternatives. Although it is not profitable for them to use fuel, they do not refuse it.

What is the secret of thermal power plants?

Thermal power plants it is no coincidence that they remain irreplaceable. Their turbine generates energy in the simplest way, using combustion. Due to this, it is possible to minimize construction costs, which are considered fully justified. There are such objects in all countries of the world, so one should not be surprised at their distribution.

The principle of operation of thermal power plants built on the combustion of huge amounts of fuel. As a result, electricity appears, which is first accumulated and then distributed to certain regions. The schemes of thermal power plants remain almost constant.

What kind of fuel does the station use?

Each station uses a separate fuel. It is specially shipped so that the workflow is not disrupted. This moment remains one of the problematic ones, as transport costs appear. What kinds of equipment does it use?

Coal;
Oil shale;
Peat;
Fuel oil;
Natural gas.

Thermal circuits of thermal power plants are based on a certain type of fuel. Moreover, minor changes are made to them, ensuring the maximum efficiency. If they are not done, the main consumption will be excessive, therefore, the resulting electric current will not justify.

Types of thermal power plants

The types of thermal power plants are an important issue. The answer will tell you how the necessary energy appears. Today, serious changes are gradually being made, where the main source will be alternative types, but so far their use remains inappropriate.

Condensing (IES);
Combined Heat and Power (CHP);
State district power plants (GRES).

The power plant TPP will require detailed description... The views are different, so only consideration will explain why construction of this scale is being carried out.

Condensing (IES)

The types of thermal power plants start with condensing ones. Such CHP plants are used exclusively for generating electricity. Most often, it accumulates without immediately spreading. The condensation method provides maximum efficiency, therefore such principles are considered optimal. Today, in all countries, separate large-scale objects are distinguished, providing vast regions.

Nuclear installations are gradually appearing to replace traditional fuel. Only replacement remains an expensive and time-consuming process, since fossil fuel operation differs from other methods. Moreover, the shutdown of any station is impossible, because in such situations, whole regions are left without valuable electricity.

Combined Heat and Power Plant (CHP)

CHP plants are used for several purposes at once. They are primarily used to generate valuable electricity, but burning fuel also remains useful for generating heat. Due to this, cogeneration power plants continue to be applied in practice.

An important feature is that these types of thermal power plants are superior to others with a relatively small capacity. They provide separate areas so there is no need for bulk supplies. Practice shows how profitable such a solution is due to the laying of additional power lines. The principle of operation of a modern thermal power plant is unnecessary only because of the environment.

State District Power Plants

General information about modern thermal power plants do not mark the GRES. Gradually, they remain in the background, losing their relevance. Although the state-owned district power plants remain useful in terms of energy production.

Different types thermal power plants provide support to vast regions, but their capacity is still insufficient. During the Soviet era, large-scale projects were carried out, which are now being closed. The reason was the inappropriate use of fuel. Although their replacement remains problematic, since the advantages and disadvantages of modern thermal power plants are primarily noted for large amounts of energy.

Which power plants are thermal? Their principle is based on fuel combustion. They remain indispensable, although they are actively calculating the equivalent replacement. Thermal power plants continue to prove their advantages and disadvantages in practice. Because of this, their work remains necessary.

Thermal power plants can be with steam and gas turbines, with internal combustion engines. The most common are thermal power plants with steam turbines, which in turn are subdivided into: condensing (IES) - all steam in which, with the exception of small extractions for heating feed water, is used to rotate the turbine, generate electrical energy; cogeneration power plants - combined heat and power plants (CHP), which are a source of power for consumers of electrical and thermal energy and are located in the area of \u200b\u200btheir consumption.

Condensing power plants

Condensing power plants are often called state district power plants (GRES). CPPs are mainly located near fuel extraction areas or reservoirs used for cooling and condensation of steam spent in turbines.

Characteristics of condensing power plants

for the most part, a significant distance from consumers of electrical energy, which makes it necessary to transmit electricity mainly at voltages of 110-750 kV;
the block principle of construction of the station, providing significant technical and economic advantages, consisting in increasing the reliability of work and facilitating the operation, in reducing the volume of construction and installation works.
The mechanisms and installations that ensure the normal functioning of the station constitute its system.

IES can operate on solid (coal, peat), liquid (fuel oil, oil) fuel or gas.

Fuel supply and preparation of solid fuel consists in transporting it from warehouses to the fuel preparation system. In this system, the fuel is brought to a pulverized state with the aim of further blowing it into the burners of the boiler furnace. To maintain the combustion process, a special fan blows air into the furnace, heated by exhaust gases, which are sucked out of the furnace by a smoke exhauster.

Liquid fuel is supplied to the burners directly from the warehouse in a heated form by special pumps.

Fuel gas preparation consists mainly of gas pressure regulation before combustion. Gas from the field or storage facility is transported through a gas pipeline to the gas distribution point (GRP) of the station. At the hydraulic fracturing, gas is distributed and its parameters are controlled.

Processes in the steam-water circuit

The main steam-water circuit carries out the following processes:

Fuel combustion in the furnace is accompanied by the release of heat, which heats up the water flowing in the boiler pipes.
Water turns into steam with a pressure of 13 ... 25 MPa at a temperature of 540 ... 560 ° C.
The steam produced in the boiler is fed to the turbine, where it performs mechanical work - it rotates the turbine shaft. As a result, the rotor of the generator also rotates, which is located on a shaft common with the turbine.
The steam spent in the turbine with a pressure of 0.003 ... 0.005 MPa at a temperature of 120 ... 140 ° C enters the condenser, where it turns into water, which is pumped out into the deaerator.
The deaerator removes dissolved gases, and above all oxygen, which is dangerous due to its corrosive activity. The circulating water supply system cools the steam in the condenser with water from external source (reservoir, river, artesian well). Chilled water having a temperature not exceeding 25 ... 36 ° C at the outlet of the condenser is discharged into the water supply system.

An interesting video about the operation of the CHPP can be viewed below:

To compensate for steam losses, make-up water is pumped into the main steam-water system, which has previously undergone chemical cleaning.

It should be noted that for the normal operation of steam-water installations, especially with overcritical steam parameters, the quality of the water supplied to the boiler is of great importance, therefore, the turbine condensate is passed through a system of desalination filters. The water treatment system is designed to purify make-up and condensate water, remove dissolved gases from it.

At stations using solid fuels, combustion products in the form of slag and ash are removed from the boiler furnace by a special slag and ash removal system equipped with special pumps.

When burning gas and fuel oil, such a system is not required.

At the IES there are significant energy losses. Heat losses in the condenser are especially high (up to 40..50% total heat generated in the furnace), as well as with waste gases (up to 10%). The efficiency of modern IES with high parameters of pressure and temperature of steam reaches 42%.

The electrical part of the KES is a set of main electrical equipment (generators) and electrical equipment for auxiliary needs, including busbars, switching and other equipment with all connections made between them.

The station generators are connected in blocks with step-up transformers without any apparatus between them.

In this regard, a generator voltage switchgear is not being built at the IES.

Switchgears for 110-750 kV, depending on the number of connections, voltage, transmitted power and the required level of reliability, are made according to standard wiring diagrams. Cross connections between blocks take place only in switchgears of the higher or in the power system, as well as for fuel, water and steam.

In this regard, each power unit can be considered as a separate autonomous station.

To provide electricity for the station's own needs, tap-off from the generators of each unit is performed. For power supply of powerful electric motors (200 kW and more) generator voltage is used, for power supply of motors of lower power and lighting installations - 380/220 V system. Electric circuits of station auxiliaries may be different.

Another interesting video about the work of the CHP plant from the inside:

Combined heat and power plants

Combined heat and power plants, being the sources of combined generation of electric and thermal energy, have a significantly higher capacity than IES (up to 75%). This is because. that part of the steam spent in turbines is used for the needs of industrial production (technology), heating, hot water supply.

This steam either directly enters for industrial and domestic needs or is partially used for preheating water in special boilers (heaters), from which water is sent to consumers of thermal energy through the heating network.

The main difference between the technology of energy production in comparison with the IES is the specificity of the steam-water circuit. Providing intermediate steam extraction of the turbine, as well as in the method of energy output, in accordance with which its main part is distributed at the generator voltage through the generator switchgear (GRU).

Communication with other stations of the power system is carried out at increased voltage through step-up transformers. In case of repair or emergency shutdown of one generator, the missing power can be transferred from the power system through the same transformers.

To increase the reliability of the CHPP, sectioning of the busbars is provided.

So, in the event of an accident on the tires and subsequent repair of one of the sections, the second section remains in operation and provides power to consumers through the lines remaining under voltage.

According to such schemes, industrial ones with generators up to 60 MW are being built, designed to supply local loads within a radius of 10 km.

Large modern generators are used with a capacity of up to 250 MW with a total plant capacity of 500-2500 MW.

These are built outside the city limits and electricity is transmitted at a voltage of 35-220 kV, GRU is not provided, all generators are connected to blocks with step-up transformers. If it is necessary to provide power to a small local load near the block, taps from the blocks between the generator and the transformer are provided. Combined schemes of the station are also possible, in which there is a GRU and several generators are connected according to block schemes.

What is and what are the principles of TPP operation? General definition of such objects sounds approximately as follows - these are power plants that convert natural energy into electrical energy. Natural fuels are also used for these purposes.

The principle of operation of TPP. Short description

To date, it is precisely on such objects that it is burned that releases heat energy that is most widespread. The task of the TPP is to use this energy to generate electricity.

The principle of operation of a TPP is the generation of not only but also the production of heat energy, which is also supplied to consumers in the form of hot water, for example. In addition, these energy facilities generate about 76% of all electricity. This widespread use is due to the fact that the availability of fossil fuel for the operation of the station is quite high. The second reason was that the transportation of fuel from the place of its production to the station itself is a rather simple and well-organized operation. The principle of operation of the TPP is built in such a way that it is possible to use the waste heat of the working fluid for its secondary supply to the consumer.

Separating stations by type

It is worth noting that thermal stations can be divided into types depending on which one they produce. If the principle of operation of a TPP consists only in the production of electrical energy (that is thermal energy does not supply to the consumer), then it is called condensing (IES).

Objects intended for the production of electrical energy, for the supply of steam, as well as the supply of hot water to the consumer, have steam turbines instead of condensing turbines. Also in such elements of the station there is an intermediate steam extraction or a back pressure device. The main advantage and principle of operation of this type of TPP (CHPP) is that waste steam is also used as a heat source and is supplied to consumers. Thus, it is possible to reduce heat loss and the amount of cooling water.

Basic principles of TPP operation

Before proceeding to consider the very principle of operation, it is necessary to understand what kind of station we are talking about. The standard arrangement of such facilities includes a system such as reheating steam. It is necessary because the thermal efficiency of a circuit with reheat will be higher than in a system where it is absent. If we talk in simple words, the principle of operation of a TPP with such a scheme will be much more efficient with the same initial and final specified parameters than without it. From all this, we can conclude that the basis of the station's work is fossil fuel and heated air.

Scheme of work

The principle of operation of the TPP is built as follows. The fuel material, as well as the oxidizer, the role of which is most often assumed by the heated air, is fed into the boiler furnace in a continuous flow. The fuel can be substances such as coal, oil, fuel oil, gas, shale, peat. If we talk about the most common fuel in the territory Russian Federationthen it is coal dust. Further, the principle of operation of a TPP is built in such a way that the heat generated by burning fuel heats the water in the steam boiler. As a result of heating, the liquid is converted into saturated steam, which is fed to the steam turbine via a steam outlet. The main purpose of this device at the station is to convert the energy of the incoming steam into mechanical energy.

All elements of the turbine capable of moving are closely connected to the shaft, as a result of which they rotate as a single mechanism. To make the shaft rotate, the kinetic energy of the steam is transferred to the rotor in a steam turbine.

The mechanical part of the station

The device and the principle of operation of the TPP in its mechanical part is associated with the operation of the rotor. The steam that comes from the turbine has a very high pressure and temperature. Because of this, a high internal energy of steam is created, which is supplied from the boiler to the turbine nozzles. The steam jets, passing through the nozzle in a continuous flow, at a high speed, which is often even higher than the sound speed, affect the turbine rotor blades. These elements are rigidly fixed to the disc, which, in turn, is closely connected to the shaft. At this point in time, the mechanical energy of the steam is converted into the mechanical energy of the rotor turbines. To be more precise about the principle of operation of a TPP, the mechanical effect affects the rotor of the turbine generator. This is due to the fact that the shaft of a conventional rotor and generator are closely connected with each other. And then a fairly well-known, simple and understandable process of converting mechanical energy into electrical energy in a device such as a generator takes place.

Steam movement after the rotor

After the water vapor passes the turbine, its pressure and temperature drop significantly, and it enters next part station - condenser. Inside this element, the reverse transformation of vapor into liquid occurs. To accomplish this task, there is cooling water inside the condenser, which is supplied there through pipes running inside the walls of the device. After the reverse transformation of steam into water, it is pumped out by a condensate pump and enters the next compartment - a deaerator. It is also important to note that the pumped-out water passes through the regenerative heaters.

The main task of the deaerator is to remove gases from the incoming water. Simultaneously with the cleaning operation, the liquid is heated in the same way as in regenerative heaters. For this purpose, the heat of the steam is used, which is taken from what goes into the turbine. The main purpose of the deaeration operation is to reduce the oxygen and carbon dioxide content in the liquid to acceptable values. This helps to reduce the rate at which corrosion affects the water and steam routes.

Coal stations

There is a high dependence of the principle of operation of the TPP on the type of fuel used. From a technological point of view, the most difficult substance to be sold is coal. Despite this, raw materials are the main source of food at such facilities, the number of which is approximately 30% of the total share of stations. In addition, it is planned to increase the number of such facilities. It is also worth noting that the number of functional compartments required for the operation of the station is much larger than that of other types.

How coal-fired TPPs work

In order for the station to work continuously, coal is constantly brought along the railroad tracks, which is unloaded using special unloading devices. Further, there are such elements as through which the unloaded coal is fed to the warehouse. Further, the fuel enters the crushing plant. If necessary, it is possible to bypass the process of supplying coal to the warehouse, and transfer it directly to the crushers from the unloading devices. After passing this stage, the crushed raw material enters the raw coal hopper. The next step is the supply of material through feeders to the pulverized coal mills. Further, the coal dust is fed into the coal dust bin using a pneumatic conveying method. Passing this path, the substance bypasses elements such as a separator and a cyclone, and from the hopper it is already supplied through the feeders directly to the burners. The air passing through the cyclone is sucked in by the mill fan and then fed into the boiler combustion chamber.

Further, the gas movement looks like this. The volatile matter formed in the combustion boiler chamber passes sequentially through such devices as boiler gas ducts, then, if a steam reheating system is used, the gas is fed to the primary and secondary superheaters. In this compartment, as well as in the water economizer, the gas gives up its heat to warm up the working fluid. Next, an element is installed called an air superheater. Here, the thermal energy of the gas is used to heat the incoming air. After passing through all these elements, the volatile substance passes into the ash collector, where it is cleaned of ash. The smoke pumps then draw the gas outside and release it into the atmosphere using a gas pipe.

TPP and NPP

Quite often, the question arises of what is common between thermal and and whether there is a similarity in the principles of operation of TPP and NPP.

If we talk about their similarities, then there are several of them. First, both of them are built in such a way that for their work they use a natural resource that is fossilized and excised. In addition, it can be noted that both objects are aimed at generating not only electrical energy, but also heat. The similarities in the principles of operation also lie in the fact that TPP and NPP have turbines and steam generators involved in the operation. Further, there are only some differences. These include the fact that, for example, the cost of construction and electricity received from thermal power plants is much lower than from nuclear power plants. But, on the other hand, nuclear power plants do not pollute the atmosphere as long as the waste is disposed of in the correct way and no accidents occur. While thermal power plants, due to their operating principle, constantly emit harmful substances into the atmosphere.

Here lies the main difference in the operation of nuclear power plants and thermal power plants. If in thermal objects thermal energy from fuel combustion is most often transferred to water or converted into steam, then at nuclear power plants energy is taken from the fission of uranium atoms. The energy obtained is used to heat a wide variety of substances and water is rarely used here. In addition, all substances are contained in closed sealed circuits.

Heating

At some TPPs, their schemes may include such a system that is engaged in heating the power plant itself, as well as the adjacent village, if any. Steam is taken from the turbine to the network heaters of this unit, and there is also a special line for condensate drainage. Water is supplied and discharged through special system pipeline. The electrical energy that will be generated in this way is removed from the electric generator and transferred to the consumer, passing through step-up transformers.

Basic equipment

If we talk about the main elements operated at thermal power plants, these are boiler houses, as well as turbine plants paired with an electric generator and a condenser. The main difference between the main equipment and the additional equipment is that it has standard parameters in terms of its power, productivity, steam parameters, as well as voltage and current, etc. It can also be noted that the type and number of main elements are selected depending on what power needs to be obtained from one TPP, as well as from the mode of its operation. Animation of the principle of operation of the TPP can help to understand this issue in more detail.

A couple of weeks ago, hot water disappeared from all the taps in Novodvinsk - there is no need to look for any intrigues of enemies here, just hydraulic tests came to Novodvinsk, a procedure necessary to prepare city energy and utilities for the new hot season. Without hot water, I somehow immediately felt like a villager - pots with boiling water on the stove - wash, shave, - wash dishes in cold water, etc.

At the same time, a question appeared in my head: how is hot water “made”, and how does it get into the taps in our apartments?

Of course, the entire city power industry is “powered” at the Arkhangelsk PPM, more precisely at TPP-1, where I went to find out where the hot water and heat in our apartments come from. Help in my search agreed chief Power Engineer Arkhangelsk PPM Andrey Borisovich Zubok, who answered many of my questions.

By the way, here is the desktop of the chief power engineer of the Arkhangelsk PPM - a monitor displaying a wide variety of data, a multichannel telephone that repeatedly rang during our conversation, a stack of documents ...

Andrey Borisovich told me how "in theory" TPP-1, the main power plant of the plant and the city, works. The very abbreviation TPP - heat and power plant - implies that the station generates not only electricity, but also heat (hot water, heating), moreover, heat generation is perhaps even more priority in our cold climate.

Scheme of TPP-1 operation:

Any heat and power plant starts from the main control panel, where all information about the processes taking place in boilers, about the operation of turbines, etc. is collected.

Here, on numerous indicators and dials, the operation of turbines, generators and boilers is visible. From here run production process station. And this process is very complicated \u003d to understand everything, you need to learn a lot.

Well, next to it is the heart of TPP-1 - steam boilers. There are eight of them at TPP-1. These are huge structures, the height of which reaches 32 meters. It is in them that the main process of energy conversion takes place, thanks to which both electricity and hot water appear in our homes - steam generation.

But it all starts with fuel. Coal, gas, peat can be used as fuel at different power plants. At TPP-1, the main fuel is coal, which is transported here from Vorkuta by rail.

Part of it is stored, the other part goes along conveyors to the station, where the coal itself is first crushed to dust and then fed through special "dust pipes" to the furnace of the steam boiler. Fuel oil is used to ignite the boiler, and then, as the pressure and temperature increase, it is transferred to coal dust.

A steam boiler is a unit for generating high-pressure steam from feed water continuously supplied to it. This is due to the heat released during the combustion of fuel. The boiler itself looks pretty impressive. This structure weighs over 1000 tons! The boiler capacity is 200 tons of steam per hour.

Outwardly, the boiler resembles a plexus of pipes, vents and some kind of mechanisms. It is hot near the boiler, because the steam leaving the boiler has a temperature of 540 degrees.

There is another boiler at TPP-1 - a modern Metso boiler with a Hybex grate, installed several years ago. The control of this power unit is displayed on a separate panel.

The unit operates on an innovative technology - combustion of fuel in a bubbly fluidized bed (Hybex). To obtain steam, bark and wood fuel (270 thousand tons per year) and sewage sludge (80 thousand tons per year) are burned here, they are brought here from treatment facilities.

A modern boiler is also a huge structure, more than 30 meters high.

Sludge and bark fuel enter the boiler through these conveyors.

And from here, after preparation, the fuel mixture goes directly into the boiler furnace.

The building of the new boiler at TPP-1 has an elevator. But there are no floors in the usual form for an ordinary city dweller - there is a height of the service mark - so the elevator moves from mark to mark.

More than 700 people work at the station. There is enough work for everyone - the equipment requires maintenance and constant monitoring by personnel. The working conditions at the station are difficult - high temperatures, humidity, noise, coal dust.

And here workers are preparing a site for the construction of a new boiler - its construction will begin next year.

Here water is prepared for the boiler. In automatic mode, the water is softened in order to reduce the negative impact on the boiler and turbine blades (already at the time when the water turns into steam).

And this is the turbine hall - steam from boilers comes here, here it turns powerful turbines (there are five of them).

Side view:

In this hall, steam works: passing through superheaters, steam is heated to a temperature of 545 degrees and enters the turbine, where under its pressure the rotor of the turbine generator rotates and, accordingly, electricity is generated.

Lots of pressure gauges.

And here it is - the turbine, where the steam works and "turns" the generator. This is turbine # 7 and, accordingly, generator # 7.

Eighth generator and eighth turbine. The generators' capacities are different, but in total they are capable of producing about 180 MW of electricity - this electricity is enough for the needs of the station itself (which is about 16%), and for the needs of the Arkhangelsk PPM production, and for providing "third-party consumers" (about 5% of the generated energy).

The interweaving of pipes is mesmerizing.

Hot water for heating (network) is obtained by heating water with steam in heat exchangers (boilers). It is pumped into the network with such pumps - there are eight of them at TPP-1. Water "for heating", by the way, is specially prepared and purified and at the outlet from the station meets the requirements for drinking water. Theoretically, this water can be drunk, but it is still not recommended to drink it due to the presence of a large amount of corrosion products in the pipes of heating networks.

And in these towers - the section of the chemical workshop of TPP-1 - water is prepared, which is added to the heating system, because part of the hot water is consumed - it must be replenished.

Further, the heated water (coolant) follows through pipelines of various cross-sections, because TPP-1 heats not only the city, but also industrial premises combine.

And electricity "leaves" the station through electrical distribution devices and transformers and is transmitted to the power system of the plant and the city.

Of course, there is a pipe at the station - the same "cloud factory". There are three such pipes at TPP-1. The highest is over 180 meters. As it turned out, the pipe is a truly hollow structure, where gas ducts from various boilers converge. Before entering the chimney, flue gases pass through an ash removal system. On a new boiler, this happens in an electrostatic precipitator. The effective degree of flue gas cleaning is 99.7%. In coal-fired boilers, cleaning is done with water - this system is less efficient, but still most of the "emissions" are captured.

Today at TPP-1, repairs are in full swing: and if the building can be renovated at any time ...

… Then major repairs of boilers or turbines can only be carried out in summer during periods of reduced loads. By the way, this is precisely why "hydraulic tests" are carried out. A programmatic increase in the load on heat supply systems is necessary, firstly, to check the reliability of public utilities, and, secondly, power engineers have the opportunity to "drain" the coolant from the system and replace, for example, a pipe section. Repair of power equipment is an expensive undertaking that requires special qualifications and admission from specialists.

Outside the plant, hot water (aka the heat carrier) flows through pipes - three "outlets" to the city provide smooth operation heating system of the city. The system is closed, water is constantly circulating in it. In the coldest time of the year - the temperature of the water leaving the station is 110 degrees Celsius, the coolant returns, having cooled down by 20-30 degrees. In summer, the temperature of the water is reduced - according to the standard at the exit from the station, it is 65 degrees Celsius.

By the way, hot water and heating are turned off not at thermal power plants, but directly in houses - management companies are engaged in this. The TPP "turns off" the water only once - after hydraulic tests in order to make repairs. After the repairs, the power engineers gradually fill the system with water - there are special mechanisms in the city for bleeding air from the system - just like in batteries in an ordinary residential building.

The end point of hot water is the same tap in any of the city apartments, but now there is no water in it - hydraulic tests.

This is how difficult it is to "do" something without which it is difficult to imagine the life of a modern city dweller - hot water.

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What are the power plants.

On the threshold of the 21st century, people increasingly began to think about what would become the basis of their existence in the new era.

Energy was and remains the main component of human life. People have gone from the first fire to nuclear power plants.

The main sources of electricity are thermal (~ 70-80%) and nuclear (10-20%).

There are types of alternative energy: solar and wind energy, sea waves and hot springs, ebbs and flows.

On the basis of these natural resources, power plants were created: wind, tidal, geothermal, solar.

Thermal power plants.

Thermal power plants operate on the following principle: fuel is burned in the furnace of a steam boiler. The heat released during combustion evaporates the water circulating inside the pipes located in the boiler and superheats the generated steam. The steam expands and rotates the turbine, which, in turn, rotates the shaft of the electric generator. The exhaust steam is then condensed; the water from the condenser is returned to the boiler through the heater system.

Thermal power plants operate on fossil fuels and are usually built near fuel extraction sites.

Thermal power plants use relatively cheap coal and fuel oil as fuel. But these fuels are irreplaceable natural resources. The main energy resources in the world today are coal (40%), oil (27%), gas (21%). These reserves, according to some estimates, will be enough, respectively, for 270, 50 and 70 years, and then on condition that humanity will spend them at the same rate as it does today.

Thermal power plants operate on fossil fuel and therefore they are built near the places of its production. Cheap coal and fuel oil are used as fuel. But, unfortunately, these are irreplaceable natural resources, which will only last for several decades. In addition, in the process of fuel combustion, harmful substances are formed that adversely affect the environment.

Thermal power plant operation scheme

Such power plants operate according to the same principle as “TPPs, but they use the energy generated by radioactive decay for vaporization.

Enriched uranium ore is used as fuel. A nuclear reactor works on the basis of a nuclear chain reaction, when the fission of one nucleus causes the fission of other nuclei; thus, the reaction maintains itself.

The practical implementation of chain reactions is not such an easy task as it looks in the diagram. The neutrons released during the fission of uranium nuclei are capable of causing fission of only the nuclei of the uranium isotope with a mass number of 235, while their energy is insufficient to destroy the nuclei of the uranium isotope with a mass number of 238. In natural uranium, uranium-238 accounts for 99.3%, and uranium-235 only 0.7%.

The minimum mass of uranium in which a chain reaction can occur is called the critical mass. The critical mass for uranium-235 is several tens of kilograms. "The first nuclear reactors were slow neutron reactors.

Slow neutrons interact well with uranium-235 nuclei and are absorbed by them 500 times more efficiently than fast ones. Therefore, when natural uranium is irradiated with slow neutrons, most of them are absorbed not in uranium-238 nuclei, but in uranium-235 nuclei and cause their fission. This means that for the development of a chain reaction in natural uranium, the neutron velocities must be reduced to thermal. Deceleration of neutrons occurs as a result of collisions with atomic nuclei of the medium in which they move. To slow down the reactor, a special substance called a moderator is used. This is usually water or graphite.

The reactor is controlled using special control rods inserted into the reactor core. The control rods are made of boron or cadmium compounds, which absorb thermal neutrons with very high efficiency. By absorbing a significant part of neutrons, they make it impossible for the development of a chain reaction. To start the reactor, the rods are removed from the core until the energy release reaches a predetermined level. With an increase in power above the set level, the automatic machines are turned on, immersing the control rods deep into the core.

Scientists are currently working on the creation of thermonuclear power plants, the advantage of which is to provide mankind with electricity for an unlimited time. A thermonuclear power plant operates on the basis of thermonuclear fusion - the reaction of fusion of heavy hydrogen isotopes with the formation of helium and the release of energy. The reaction of thermonuclear fusion does not produce gaseous and liquid radioactive waste, does not produce plutonium, which is used for the production of nuclear weapons. If we also take into account that the fuel for thermonuclear stations will be the heavy isotope of hydrogen deuterium, which is obtained from simple water - half a liter of water contains fusion energy equivalent to that obtained by burning a barrel of gasoline - then the advantages of power plants based on a thermonuclear reaction, become apparent.

International thermonuclear reactor ITER.

I would like to believe that the era of environmentally hazardous hydroelectric power plants and nuclear power plants will soon end, and the time will come for new power plants - thermonuclear. But, despite the fact that the ITER (International Thermonuclear Reactor) project is almost ready; Despite the fact that already at the first operating experimental thermonuclear reactors a power exceeding 10 MW was obtained - the level of the first nuclear power plants, the first thermonuclear power plant will start working no earlier than twenty years later, because its cost is very high. For example, the construction of ITER requires, according to the most conservative estimates, from 8 to 10 billion dollars and 10 years of work. These figures are deeply embarrassing for the project participants, the United States even left it.

Wind power plants.

The principle of operation of wind power plants is simple: the wind turns the blades of a windmill, driving the shaft of an electric generator. The generator, in turn, generates electrical energy. It turns out that wind farms work like toy cars on batteries, only the principle of their operation is the opposite. Instead of converting electrical energy into mechanical energy, wind energy is converted into electrical current.

To obtain wind energy, different designs are used: multi-blade "daisies"; propellers like aircraft propellers with three, two or even one blade (then it has a counterweight); vertical rotors resembling a barrel cut along and mounted on an axis; some semblance of a "standing on end" helicopter propeller: the outer ends of its blades are bent upward and connected to each other. The good thing about vertical structures is that they catch the wind from any direction. The rest have to turn in the wind.

Wind turbines are very cheap to manufacture, but their capacity is small and their operation depends on the weather. In addition, they are very noisy, so large installations even have to be turned off at night. In addition, wind farms interfere with air traffic and even radio waves. The use of wind turbines causes a local weakening of the force of air currents, which interferes with the ventilation of industrial areas and even affects the climate. Finally, their use requires huge areas, much more than for other types of power generators.

Tidal power plants.

Power plants of this type use tidal energy to generate electricity. The first such power plant (Pauzhetskaya) with a capacity of 5 MW was built in Kamchatka. For the construction of the simplest tidal power plant (TES), a pool is needed - a bay or river mouth blocked by a dam. The dam has culverts and turbines that turn a generator. At high tide, water enters the pool. When the water levels in the basin and the sea become equal, the culverts are closed. With the onset of low tide, the water level in the sea decreases, and when the pressure becomes sufficient, the turbines and electric generators connected to it begin to work, and the water from the pool gradually leaves.

It is considered economically feasible to build tidal power plants in areas with tidal fluctuations in sea level of at least 4 m. The design capacity of a tidal power plant depends on the nature of the tide in the area of \u200b\u200bthe station construction, on the volume and area of \u200b\u200bthe tidal basin, on the number of turbines installed in the dam body.

In double-acting tidal power plants, turbines operate by moving water from the sea to the basin and vice versa. Double-acting tidal power plants are capable of generating electricity continuously for 4-5 hours with intervals of 1-2 hours four times a day. To increase the operating time of turbines, there are more complex schemes - with two, three and more pools, but the cost of such projects is very high. The disadvantage of tidal power plants is that they are built only on the shores of the seas and oceans, moreover, they do not develop very high power, and the tides are only twice a day. And even they are not environmentally friendly.

They disrupt the normal exchange of salt and fresh water and thus - the living conditions of marine flora and fauna. They also affect the climate, since they change the energy potential of sea waters, their speed and territory of movement. Offshore thermal power plants, built on the difference in sea water temperatures, contribute to the release of a large amount of carbon dioxide, heating and lowering the pressure of deep waters and cooling surface waters. And these processes cannot but affect the climate, flora and fauna of the region.

Power plants of this type convert the internal heat of the Earth (energy from hot steam and water sources) into electricity.

The first geothermal power plant was built in Kamchatka. There are several schemes for generating electricity at a geothermal power plant.

Direct scheme: natural steam is sent through pipes to turbines connected to power generators.

Indirect scheme: steam is preliminarily (before entering the turbines) cleaned of gases that cause pipe destruction. Mixed scheme: untreated steam enters the turbines, and then gases not dissolved in it are removed from the water formed as a result of condensation.

The disadvantages of geothermal electrical installations include the possibility of local subsidence of soils and the awakening of seismic activity. And gases escaping from the ground create a lot of noise in the vicinity and may, moreover, contain toxic substances. In addition, it is not possible to build a geothermal power plant everywhere, because certain geological conditions are necessary for its construction.

Solar power plants.

Currently, solar power plants are being built mainly of two types: solar power plants of a tower type and solar power plants of a distributed (modular) type.

Tower solar power plants use a central receiver with a heliostat field providing a concentration of several thousand. The tracking system for the Sun is significantly complex as it requires rotation around two axes. The system is controlled by a computer. As a working medium in a heat engine, water vapor with a temperature of up to 550єC is usually used, air and other gases - up to 1000єC, low-boiling organic liquids (including freons) - up to 100єC, liquid metal coolants - up to 800єC.

The main disadvantages of tower solar power plants are their high cost and large footprint. So, to locate a solar power plant with a capacity of 100 MW, an area of \u200b\u200b200 hectares is required, and for a nuclear power plant with a capacity of 1000 MW - only 50 hectares. Tower solar power plants with a capacity of up to 10 MW are unprofitable, their optimal capacity is 100 MW, and the tower height is 250 m.

In distribution (modular) type solar power plants, a large number of modules are used, each of which includes a parabolic-cylindrical concentrator of solar radiation and a receiver located in the focus of the concentrator and used to heat the working fluid supplied to the heat engine, which is connected to an electric generator. The largest solar power plant of this type was built in the USA and has a capacity of 12.5 MW.

With low power, modular solar power plants are more economical than tower ones. In modular solar power plants, linear solar concentrators are usually used with a maximum concentration of about 100.

The energy of solar radiation can be converted into direct electric current through solar panels - devices consisting of thin films of silicon or other semiconductor materials. The advantage of photoelectric converters (PEC) is due to the absence of moving parts, their high reliability and stability. Moreover, their service life is practically unlimited. They are lightweight, easy to maintain, and efficiently use both direct and diffuse solar radiation. The modular type of structures allows you to create installations of almost any capacity and makes them very promising. The disadvantage of FEP is its high cost and low efficiency (currently almost 10-12%).

Solar batteries are still used mainly in space, and on Earth only for power supply of autonomous consumers with a capacity of up to 1 kW, power supply of radio navigation and low-power electronic equipment, drive experimental electric vehicles and aircraft. In 1988, the first worldwide solar car rally took place in Australia. As solar batteries improve, they will be used in residential buildings for autonomous power supply, i.e. heating and hot water supply, as well as for the generation of electricity for lighting and power supply of household electrical appliances.

Hydroelectric power plants.

Hydroelectric power plants convert the energy of the water flow into electricity by means of hydraulic turbines that drive electric generators. A hydroelectric power plant is most efficient when the water flow falls on the turbine from above. For these purposes, a dam is being built that raises the water level in the river and concentrates the water pressure at the location of the turbines.

The scheme of the hydroelectric power plant:

The energy of the moving water is converted into electricity by supplying it directly to the turbine.

When a dam is built, a reservoir is formed. Water that has flooded vast areas irreversibly changes the environment. A rise in the level of a river by a dam can cause waterlogging, salinity, changes in coastal vegetation and microclimate. In addition, the dam blocks the path of fish going to spawn. Fields and forests are flooded, people are being evicted from their homes.

Renewable energies.

Many different ideas and proposals are being put forward for the use of all kinds of renewable energy. Even manure can be a source of energy! Not only manure is used as fuel, but also its products. Manure is processed more often together with municipal waste. The fact is that both types of biomass contain microorganisms that, under certain conditions (in particular, at a temperature of 50-60єC, without air access), decompose organic matter into biogas. This process necessarily takes place with the participation of special substances - enzymes - and therefore is called fermentation.

Animal waste processing scheme.

The waste goes through a pipeline to the power plant, where it is biologically processed in a special reactor. The resulting gas is used to generate electricity, and the waste processed by bacteria is used for fertilization. electric fusion reactor

Power plants with an internal combustion engine.

It is believed that the outstanding Dutch mathematician H. Huygens is the inventor of the internal combustion engine (ICE). However, the engine he proposed was not built. In 1866 German scientists Langen and N. Otto created a more efficient gas engine. And in 1891 the German engineer R. Diesel built an internal combustion engine with compression ignition. The idea and principle of operation of the Rudolf Diesel engine was stated as follows:

A working process in an internal combustion engine, characterized in that the piston in the cylinder compresses the air or a mixture of some other indifferent gas (vapor) with air so strongly that the resulting compression temperature significantly exceeds the ignition temperature of the fuel; in this case, the combustion of the fuel gradually introduced after the dead center occurs in such a way that no significant increase in pressure and temperature occurs in the engine cylinder.

When carrying out the working process described above, a multistage compressor with a receiver is connected to the working cylinder. Likewise, it is possible to connect several working cylinders with each other or with cylinders for preliminary compression and subsequent expansion.

A year after receiving the patent, the theoretical part of Diesel's work was described by him in the brochure "Theory and design of a rational heat engine designed to replace the steam engine and other currently existing engines." In such an engine, Diesel believed, an increase in the temperature of the expanding gas mixture should be made not only as a result of fuel combustion, but also before the start of this process - by preliminary compression of clean air in the cylinder. The "rational engine", like Otto's gas engines, had to work 1 in a four-stroke cycle.

However, the latter did not suck in clean air, but a working mixture consisting of air and gaseous fuel, which did not allow, due to the possibility of premature ignition of the mixture, to reach high compression ratios. Fresh airsucked in through the Diesel cycle could be adjusted to any technically feasible compression ratio. If in Otto engines the mixture was ignited by an electric spark, then in the Diesel engine the hot air itself ignited the incoming fuel. Finally, Diesel planned to implement a gradual combustion of fuel as it came in without a significant increase in the temperature in the cylinder during the stroke stage, while in the Otto engine the mixture burned out quickly, almost explosively. Thus, Diesel hoped to get close to the realization of the Carnot thermodynamic cycle.

A hundred-year history of ICE development combined with the latest advances in electronics and computing technology contributed to the creation of modern power plants with internal combustion engines.

Nowadays, compact mobile power plants are becoming the subject of everyday use. Home power plants that run on gasoline and diesel fuel allow them to supply electricity to the house autonomously, without a centralized power grid, so they are increasingly used in cottages and summer cottages. Autonomous power generators do not take up much space, while some models provide an automatic start system with switching the consumer to the power plant (auto start). In this case, approximately 20-50 seconds after the power supply is cut off, all switched on household electrical appliances can be "revived" by the home power plant, and when the centralized power supply is restored, it will automatically turn off with a power interruption to the network for only 2-5 seconds.

Components of a diesel / gasoline generating set.

A home power plant consists of an internal combustion engine (carburetor or diesel) that drives a generator that generates electricity at 220 or 380 V at 50 Hz. Synchronous generators are more commonly used, although they can also be asynchronous. In some models of electric generators, a three-phase voltage of 380 or 400 V is provided, as well as a constant voltage of 12 V for recharging the car's battery. Power plants with a carburetor engine run on gasoline (usually of the AI-92 brand), and those with a diesel engine run on diesel fuel. The simplest engine used is the air-cooled single-cylinder two-stroke, and the most complex is the water-cooled twelve-cylinder four-stroke diesel engine.

Power plants differ in the values \u200b\u200bof operating parameters: power, resource, efficiency, and a number of others.

Their power can be from 0.35 kW to 500 kW or more, but for home use it usually does not exceed 5-20 kW. It should be noted that gasoline power generators have a capacity of 0.35 to 11 kW, while diesel power plants - from 2.5 kW and more.

Another important parameter is the resource of guaranteed uptime before the first overhaul power plant, measured in engine hours. According to it, power plants can be conditionally divided into three groups - seasonal (with a resource from 500 to 1000 operating hours), robustas - only for powering household appliances and power tools (with a resource from 1500 to 2500 operating hours) and long-term use (with a resource of 3000 operating hours and more). The cost of a power plant, both gasoline and diesel, grows in proportion to its resource.

The third operating parameter is fuel consumption, expressed in liters of fuel consumed for one hour of continuous engine operation, or in abbreviated form - l / hour. Having these data, it is possible to calculate the efficiency of the power plant, which is estimated at the cost of one hour of its operation in rubles.

This article discusses a far from complete list of ways to generate electricity and, accordingly, not all types of power plants. This article will be updated as new information becomes available.

Posted on Allbest.ru

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