The operating principle of a combined heat and power plant (CHP) is based on the unique property of water vapor - to be a coolant. In a heated state, under pressure, it turns into a powerful source of energy that drives the turbines of thermal power plants (CHPs) - a legacy of the already distant era of steam.
The first thermal power plant was built in New York on Pearl Street (Manhattan) in 1882. A year later, St. Petersburg became the birthplace of the first Russian thermal station. Oddly enough, even in our age of high technology, thermal power plants have not yet found a full-fledged replacement: their share in the world energy sector is more than 60%.
And there is a simple explanation for this, which contains the advantages and disadvantages of thermal energy. Its “blood” is organic fuel - coal, fuel oil, oil shale, peat and natural gas are still relatively accessible, and their reserves are quite large.
The big disadvantage is that fuel combustion products cause serious harm to the environment. Yes, and the natural storehouse will one day be completely depleted, and thousands of thermal power plants will turn into rusting “monuments” of our civilization.
Definition
A thermal power plant is a power plant that uses any fossil fuel as an energy source. The latter can be used, for example, oil, gas, coal. Currently, thermal complexes are the most common type of power plants in the world. The popularity of thermal power plants is explained primarily by the availability of fossil fuels. Oil, gas and coal are available in many parts of the planet.
TPP is (the abbreviation itself looks like “thermal power plant”), among other things, a complex with a fairly high efficiency. Depending on the type of turbines used, this figure at stations of this type can be 30 - 70%.
What is the secret of thermal power plants?
It is no coincidence that thermal power plants remain indispensable. Their turbine produces energy in the simplest way, using combustion. Due to this, it is possible to minimize construction costs, which are considered completely justified. There are such objects in all countries of the world, so one should not be surprised at the spread.
The operating principle of thermal power plants is based on burning huge volumes of fuel. As a result, electricity appears, which is first accumulated and then distributed to certain regions. Thermal power plant patterns remain almost constant.
What types of thermal power plants are there?
Stations of this type can be classified according to two main criteria:
- purpose;
- type of installations.
In the first case, a distinction is made between state district power plants and thermal power plants. A state district power plant is a station that operates by rotating a turbine under the powerful pressure of a steam jet. The deciphering of the abbreviation GRES - state district power plant - has currently lost its relevance. Therefore, such complexes are often also called CES. This abbreviation stands for “condensing power plant”.
CHP is also a fairly common type of thermal power plant. Unlike state district power plants, such stations are equipped not with condensation turbines, but with heating turbines. CHP stands for “heat and power plant”.
In addition to condensation and heating plants (steam turbine), the following types of equipment can be used at thermal power plants:
- gas turbine units;
- steam-gas.
Types of thermal power plants
The article discusses the types of thermal power plants and their classification according to various criteria. And also their definitions and characteristics are given.
Human life is associated with the widespread use of not only electrical, but also thermal energy. It is important to immediately understand that the heat used by a person for domestic needs is low potential, i.e. its coolant has a relatively low temperature and pressure, since this is what makes it possible to organize highly economical production of electrical and thermal energy at thermal power plants, which will mainly be discussed below. In general, the supply of thermal energy to any object is provided by a system consisting of three main elements: a heat source (for example, a boiler room), a heating network (for example, hot water or steam pipelines) and a heat receiver (for example, a water heating radiator located in the room) [ 1].
A thermal power plant is a complex of equipment and devices that convert fuel energy into electrical and (in general) thermal energy.
Thermal power plants are characterized by great diversity and can be classified according to various criteria.
- Based on their purpose and type of energy supplied, power plants are divided into regional and industrial.
District power plants are independent public power plants that serve all types of consumers in the region (industrial enterprises, transport, population, etc.). District condensing power plants, which generate mainly electricity, often retain their historical name - GRES (state district power plants). District power plants that produce electrical and thermal energy (in the form of steam or hot water) are called combined heat and power plants (CHP). As a rule, state district power plants and district thermal power plants have a capacity of more than 1 million kW.
Industrial power plants are power plants that supply thermal and electrical energy to specific production enterprises or their complex, for example, a chemical production plant. Industrial power plants are part of the industrial enterprises they serve. Their capacity is determined by the needs of industrial enterprises for thermal and electrical energy and, as a rule, it is significantly less than that of district thermal power plants. Often industrial power plants operate on the general electrical network, but are not subordinate to the power system dispatcher. Only district power plants are considered below.
2. Based on the type of fuel used, thermal power plants are divided into power plants operating on organic fuel and nuclear fuel.
Condensing power plants running on fossil fuels, at a time when there were no nuclear power plants (NPPs), were historically called thermal power plants (TES - thermal power plant). It is in this sense that this term will be used below, although thermal power plants and nuclear power plants, gas turbine power plants (GTPPs) and combined cycle power plants (CGPPs) are also thermal power plants operating on the principle of converting thermal energy into electrical energy.
Gaseous, liquid and solid fuels are used as organic fuel for thermal power plants. Most thermal power plants in Russia, especially in the European part, consume natural gas as the main fuel, and fuel oil as a backup fuel, using the latter, due to its high cost, only in extreme cases; Such thermal power plants are called gas-oil power plants. In many regions, mainly in the Asian part of Russia, the main fuel is thermal coal - low-calorie coal or high-calorie coal waste (anthracite coal - AS). Since before combustion such coals are ground in special mills to a dusty state, such thermal power plants are called pulverized coal.
- Based on the type of thermal power plants used at thermal power plants to convert thermal energy into mechanical energy of rotation of the rotors of turbine units, steam turbine, gas turbine and combined cycle power plants are distinguished.
The basis of steam turbine power plants are steam turbine units (STU), which use the most complex, most powerful and extremely advanced energy machine - a steam turbine - to convert thermal energy into mechanical energy. PTU is the main element of thermal power plants, combined heat and power plants and nuclear power plants.
Gas turbine thermal power plants (GTPPs) are equipped with gas turbine units (GTUs) running on gaseous or, in extreme cases, liquid (diesel) fuel. Since the temperature of the gases behind the gas turbine plant is quite high, they can be used to supply thermal energy to external consumers. Such power plants are called GTU-CHP. Currently, in Russia there is one gas turbine power plant (GRES-3 named after Klasson, Elektrogorsk, Moscow region) with a capacity of 600 MW and one gas turbine cogeneration plant (in the city of Elektrostal, Moscow region).
Combined-cycle thermal power plants are equipped with combined cycle gas units (CCGs), which are a combination of gas turbines and steam turbines, which allows for high efficiency. CCGT-CHP plants can be designed as condensing plants (CCP-CHP) and with thermal energy supply (CCP-CHP). In Russia there is only one operating CCGT-CHP (PGU-450T) with a capacity of 450 MW. At the Nevinnomyssk State District Power Plant there is a power unit (see lecture 7) PGU-170 with a capacity of 170 MW, and at the South Thermal Power Plant of St. Petersburg there is a power unit PGU-300 with a capacity of 300 MW.
- According to the technological scheme of steam pipelines, thermal power plants are divided into block thermal power plants and thermal power plants with cross connections.
Modular thermal power plants consist of separate, usually of the same type, power plants - power units. In the power unit, each boiler supplies steam only to its turbine, from which it returns after condensation only to its boiler. All powerful state district power plants and thermal power plants, which have the so-called intermediate superheating of steam, are built according to the block scheme. The operation of boilers and turbines at thermal power plants with cross connections is ensured differently: all boilers of the thermal power plant supply steam to one common steam line (collector) and all steam turbines of the thermal power plant are powered from it. According to this scheme, CESs without intermediate overheating and almost all CHP plants with subcritical initial steam parameters are built.
- Based on the level of initial pressure, thermal power plants of subcritical pressure and supercritical pressure (SCP) are distinguished.
The critical pressure is 22.1 MPa (225.6 at). In the Russian heat and power industry, the initial parameters are standardized: thermal power plants and combined heat and power plants are built for subcritical pressure of 8.8 and 12.8 MPa (90 and 130 atm), and for SKD - 23.5 MPa (240 atm). TPPs with supercritical parameters, for technical reasons, are performed with intermediate overheating and according to a block diagram. Often thermal power plants or combined heat and power plants are built in several stages - in queues, the parameters of which are improved with the commissioning of each new queue [2].
LITERATURE
- Trukhniy A.D. Stationary steam turbines. – M.: Energoatomizdat, 1990. – P. 114.
- Energy in Russia and in the world: Problems and prospects. – M.: MAIK “Nauka/Inter-periodika”, 2001. – 302 p.
TPP and CHP: differences
Often people confuse these two concepts. CHP, in fact, as we found out, is one of the types of thermal power plants. Such a station differs from other types of thermal power plants primarily in that part of the thermal energy it generates goes to boilers installed in the premises to heat them or to produce hot water.
Also, people often confuse the names of hydroelectric power stations and state district power stations. This is primarily due to the similarity of abbreviations. However, a hydroelectric power station is fundamentally different from a state district power station. Both of these types of stations are built on rivers. However, at a hydroelectric power station, unlike state regional power plants, it is not steam that is used as an energy source, but the water flow itself.
What are the requirements for thermal power plants?
A thermal power plant is a thermal power station where electricity is generated and consumed simultaneously. Therefore, such a complex must fully comply with a number of economic and technological requirements. This will ensure uninterrupted and reliable supply of electricity to consumers. So:
- thermal power plant premises must have good lighting, ventilation and aeration;
- the air inside and around the plant must be protected from contamination by solid particles, nitrogen, sulfur oxide, etc.;
- water supplies should be carefully protected from the ingress of wastewater;
- Water treatment systems at stations should be waste-free.
Operating principle of thermal power plants
A thermal power plant is a power plant that can use turbines of various types. Next, we will consider the principle of operation of thermal power plants using the example of one of its most common types - thermal power plants. Energy is generated at such stations in several stages:
- Fuel and oxidizer enter the boiler. Coal dust is usually used as the first in Russia. Sometimes the fuel for thermal power plants can also be peat, fuel oil, coal, oil shale, and gas. In this case, the oxidizing agent is heated air.
- The steam generated as a result of burning fuel in the boiler enters the turbine. The purpose of the latter is to convert steam energy into mechanical energy.
- The rotating shafts of the turbine transmit energy to the shafts of the generator, which converts it into electricity.
- The cooled steam that has lost some of its energy in the turbine enters the condenser. Here it turns into water, which is supplied through heaters to the deaerator.
- Deaerated water is heated and supplied to the boiler.
Five of the most powerful thermal power plants in the world
The championship belongs to the Chinese thermal power plant Tuoketuo with a capacity of 6600 MW (5 power units x 1200 MW), occupying an area of 2.5 square meters. km. It is followed by its “compatriot” - the Taichung Thermal Power Plant with a capacity of 5824 MW. The top three is closed by the largest in Russia Surgutskaya GRES-2 - 5597.1 MW. In fourth place is the Polish Belchatow Thermal Power Plant - 5354 MW, and fifth is the Futtsu CCGT Power Plant (Japan) - a gas thermal power plant with a capacity of 5040 MW.
The operating cycle of a thermal power plant involves a constant supply of heat. Heat is produced by burning fuel. Our country has a large number of thermal power plants (CHP, state district power plant), but they all use 3-4 types of fuel. These are natural gas, coal (hard and brown), fuel oil and peat. The most common types of fuel are gas and coal.
Advantages of TPP
A thermal power plant is thus a station whose main type of equipment is turbines and generators. The advantages of such complexes include primarily:
- low cost of construction compared to most other types of power plants;
- cheapness of the fuel used;
- low cost of electricity generation.
Also, a big advantage of such stations is that they can be built in any desired location, regardless of the availability of fuel. Coal, fuel oil, etc. can be transported to the station by road or rail.
Another advantage of thermal power plants is that they occupy a very small area compared to other types of stations.
Nuclear power plants: advantages and disadvantages
We examined in detail the advantages and disadvantages of nuclear power plants over other methods of generating electricity.
“But what about radioactive emissions from nuclear power plants? It is impossible to live near nuclear power plants! Is it dangerous!" - you say. “Nothing like that,” statistics and the world scientific community will answer you.
According to statistical comparative estimates carried out in different countries, it is noted that the mortality rate from diseases that appeared from exposure to emissions from thermal power plants is higher than the mortality rate from diseases that developed in the human body from the leakage of radioactive substances.
Actually, all radioactive substances are firmly locked in storage facilities and are waiting for the hour when they will learn to reprocess and use them. Such substances are not released into the atmosphere; the level of radiation in populated areas near nuclear power plants is no more than the traditional level of radiation in large cities.
Speaking about the advantages and disadvantages of nuclear power plants, one cannot help but recall the cost of building and launching a nuclear power plant. The estimated cost of a small modern nuclear power plant is 28 billion euros, experts say that the cost of thermal power plants is approximately the same, no one wins here. However, the advantages of nuclear power plants will be lower costs for the purchase and disposal of fuel - uranium, although more expensive, can “work” for more than a year, while coal and gas reserves must be constantly replenished.
What other types of thermal power plants exist?
In addition to steam turbine thermal power plants and thermal power plants (GRES), the following stations operate in Russia:
- Gas turbine (GTPP). In this case, the turbines rotate not from steam, but from natural gas. Also, fuel oil or diesel fuel can be used as fuel at such stations. The efficiency of such stations, unfortunately, is not too high (27 - 29%). Therefore, they are mainly used only as backup sources of electricity or intended to supply voltage to the network of small settlements.
- Steam-gas turbine (SGPP). The efficiency of such combined stations is approximately 41 - 44%. In systems of this type, both gas and steam turbines simultaneously transmit energy to the generator. Like thermal power plants, combined hydroelectric power plants can be used not only for generating electricity itself, but also for heating buildings or providing consumers with hot water.
In what cases is this equipment chosen?
When the costs of transmitting or producing electricity are high and the budget of an organization or individual cannot bear them. If centralized systems for supplying heat and electricity cannot cope with additionally constructed or commissioned areas.
When the amount of electricity is simply not enough for the smooth operation of modern equipment and devices. Or it is of low quality. We also must not forget about the environmental component of the equipment, which allows the release of harmful substances into the atmosphere.
Examples of stations
So, any thermal power plant or power plant can be considered quite productive and to some extent even a universal object. We present examples of such complexes in the list below.
- Belgorod Thermal Power Plant. The power of this station is 60 MW. Its turbines run on natural gas.
- Michurinskaya CHPP (60 MW). This facility is also located in the Belgorod region and runs on natural gas.
- Cherepovets GRES. The complex is located in the Volgograd region and can operate on both gas and coal. The power of this station is as much as 1051 MW.
- Lipetsk CHPP-2 (515 MW). Powered by natural gas.
- CHPP-26 "Mosenergo" (1800 MW).
- Cherepetskaya GRES (1735 MW). The fuel source for the turbines of this complex is coal.
