What is it and what are the operating principles of thermal power plants? General definition of such objects sounds approximately as follows - this power plants who are engaged in processing natural energy to electric. Fuel of natural origin is also used for these purposes.
The operating principle of thermal power plants. Short description
To date greatest distribution received exactly At such facilities it is burned which emits thermal energy. The task of thermal power plants is to use this energy to produce electrical energy.
The operating principle of thermal power plants is not only the generation but also the production of thermal 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 fuels for the operation of the station is quite high. The second reason was that transporting fuel from the place of its extraction to the station itself is a fairly simple and streamlined operation. The operating principle of thermal power plants is designed in such a way that it is possible to use the waste heat of the working fluid for its secondary supply to the consumer.
Separation of stations by type
It is worth noting that thermal stations can be divided into types depending on what kind they produce. If the principle of operation of a thermal power plant is only to produce electrical energy (that is, it does not supply thermal energy to the consumer), then it is called condensing power plant (CES).
Facilities 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 backpressure device. The main advantage and operating principle of this type of thermal power plant (CHP) is that waste steam is also used as a heat source and supplied to consumers. This reduces heat loss and the amount of cooling water.
Basic operating principles of thermal power plants
Before moving on to considering the principle of operation itself, it is necessary to understand exactly which station we're talking about. Standard device of such objects includes a system such as intermediate superheating of steam. It is necessary because the thermal efficiency of a circuit with intermediate superheating will be higher than in a system without it. If we talk in simple words, the operating principle of a thermal power plant 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 operation is organic fuel and heated air.
Scheme of work
The operating principle of the thermal power plant is constructed as follows. The fuel material, as well as the oxidizer, the role of which is most often played by heated air, is fed in a continuous flow into the boiler furnace. Substances such as coal, oil, fuel oil, gas, shale, and peat can act as fuel. If we talk about the most common fuel in the territory Russian Federation, then it is coal dust. Further, the operating principle of thermal power plants is constructed 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 enters the steam turbine through the 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 that can move are closely connected to the shaft, as a result of which they rotate as a single mechanism. To make the shaft rotate, a steam turbine transfers the kinetic energy of steam to the rotor.
Mechanical part of the station
The design and principle of operation of a thermal power plant in its mechanical part is associated with the operation of the rotor. The steam that comes from the turbine has very high pressure and temperature. This creates a high internal energy steam, which comes from the boiler to the turbine nozzles. Jets of steam, passing through the nozzle in a continuous flow, at high speed, which is often even higher than sound speed, act on the turbine blades. These elements are rigidly fixed to the disk, which, in turn, is closely connected to the shaft. At this point in time a transformation occurs mechanical energy steam into mechanical energy of rotor turbines. If we talk more precisely about the principle of operation of thermal power plants, then the mechanical impact affects the rotor of the turbogenerator. This is due to the fact that the shaft of a conventional rotor and generator are tightly coupled to each other. And then there is a fairly well-known, simple and understandable process of converting mechanical energy into electrical energy in a device such as a generator.
Steam movement after the rotor
After the water vapor passes the turbine, its pressure and temperature drop significantly, and it enters the next part of the station - the condenser. Inside this element, the vapor is converted back into liquid. To perform this task, there is cooling water inside the condenser, which is supplied there through pipes running inside the walls of the device. After the steam is converted back into water, it is pumped out by a condensate pump and enters the next compartment - the deaerator. It is also important to note that the pumped water passes through 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 content and carbon dioxide in liquid to acceptable values. This helps reduce the rate of corrosion on the paths through which water and steam are supplied.
Coal stations
There is a high dependence of the operating principle of thermal power plants on the type of fuel used. From a technological point of view, the most difficult substance to implement is coal. Despite this, raw materials are the main source of power 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 objects. It is also worth noting that the number of functional compartments required for the operation of the station is much greater than that of other types.
How do thermal power plants run on coal fuel?
In order for the station to operate continuously, railway tracks Coal is constantly brought in, which is unloaded using special unloading devices. Then there are elements such as through which unloaded coal is supplied to the warehouse. Next, the fuel enters the crushing plant. If necessary, it is possible to bypass the process of delivering coal to the warehouse and transfer it directly to the crushers from unloading devices. After passing this stage, the crushed raw materials enter the raw coal bunker. The next step is to supply the material through feeders to the pulverized coal mills. Next, the coal dust, using a pneumatic transportation method, is fed into the coal dust bunker. Along this path, the substance bypasses elements such as a separator and a cyclone, and from the hopper it already flows 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 combustion chamber of the boiler.
Further, the gas movement looks approximately as follows. The volatile substance formed in the chamber of the combustion boiler passes sequentially through such devices as the gas ducts of the boiler plant, then, if a steam reheat system is used, the gas is supplied to the primary and secondary superheater. In this compartment, as well as in the water economizer, the gas gives up its heat to heat the working fluid. Next, an element called an air superheater is installed. Here the thermal energy of the gas is used to heat the incoming air. After going through all these elements, volatile substance goes to the ash collector, where it is cleaned of ash. After this, smoke pumps draw the gas out and release it into the atmosphere using a gas pipe.
Thermal power plants and nuclear power plants
Quite often the question arises about what is common between thermal power plants and whether there are similarities in the operating principles of thermal power plants and nuclear power plants.
If we talk about their similarities, there are several of them. Firstly, both of them are built in such a way that they use natural resource, being a fossil and excised. In addition, it can be noted that both objects are aimed at generating not only electrical energy, but also thermal energy. The similarities in operating principles also lie in the fact that thermal power plants and nuclear power plants have turbines and steam generators involved in the operation process. Further there are only some differences. These include the fact that, for example, the cost of construction and electricity obtained 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 correctly 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 the thermal energy from fuel combustion is most often transferred to water or converted into steam, then nuclear power plants energy comes from the fission of uranium atoms. The resulting energy is used to heat a variety of substances and water is used here quite rarely. In addition, all substances are contained in closed, sealed circuits.
District heating
At some thermal power plants, their design may include a system that handles heating of the power plant itself, as well as the adjacent village, if there is one. To the network heaters of this installation, steam is taken from the turbine, and there is also a special line for condensate removal. Water is supplied and discharged through special system pipeline. Ta Electric Energy, which will be generated in this way, is taken away from the electric generator and transmitted 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 units paired with an electric generator and a capacitor. 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 how much power needs to be obtained from one thermal power plant, as well as its operating mode. An animation of the operating principle of thermal power plants can help to understand this issue in more detail.
CHP - thermal power plant, which produces not only electricity, but also provides heat to our homes in winter. Using the example of the Krasnoyarsk Thermal Power Plant, let’s see how almost any thermal power plant works.
There are 3 thermal power plants in Krasnoyarsk, the total electrical power of which is only 1146 MW (for comparison, our Novosibirsk CHPP 5 alone has a capacity of 1200 MW), but what was remarkable for me was Krasnoyarsk CHPP-3 because the station is new - not even a year has passed , as the first and so far only power unit was certified by the System Operator and put into commercial operation. Therefore, I was able to photograph the still dusty, beautiful station and learn a lot about the thermal power plant.
In this post, in addition to technical information about KrasTPP-3, I want to reveal the very principle of operation of almost any combined heat and power plant.
1.
Three chimneys, the height of the highest one is 275 m, the second highest is 180 m
The abbreviation CHP itself implies that the station generates not only electricity, but also heat ( hot water, heating), and heat generation is perhaps even more of a priority in our country, known for its harsh winters.
2.
The installed electrical capacity of Krasnoyarsk CHPP-3 is 208 MW, and the installed thermal capacity is 631.5 Gcal/h
In a simplified way, the operating principle of a thermal power plant can be described as follows:
It all starts with fuel. Coal, gas, peat, and oil shale can be used as fuel at different power plants. In our case, this is B2 brown coal from the Borodino open-pit mine, located 162 km from the station. Coal is transported by rail. Part of it is stored, the other part goes along conveyors to the power unit, where the coal itself is first crushed to dust and then fed into the combustion chamber - the steam boiler.
A steam boiler is a unit for producing steam at a pressure above atmospheric pressure from feed water continuously supplied to it. This happens due to the heat released during fuel combustion. The boiler itself looks quite impressive. At KrasCHETS-3, the height of the boiler is 78 meters (26-story building), and it weighs more than 7,000 tons.
6.
Steam boiler brand Ep-670, manufactured in Taganrog. Boiler capacity 670 tons of steam per hour
I borrowed a simplified diagram of a power plant steam boiler from the website energoworld.ru so that you can understand its structure 
1 - combustion chamber (furnace); 2 - horizontal gas duct; 3 - convective shaft; 4 - combustion screens; 5 - ceiling screens; 6 — drain pipes; 7 - drum; 8 – radiation-convective superheater; 9 - convective superheater; 10 - water economizer; 11 — air heater; 12 — blower fan; 13 — lower screen collectors; 14 - slag chest of drawers; 15 — cold crown; 16 - burners. The diagram does not show the ash collector and smoke exhauster.
7.
View from above
10.
The boiler drum is clearly visible. The drum is a cylindrical horizontal vessel having water and steam volumes, which are separated by a surface called the evaporation mirror.
Due to its high steam output, the boiler has developed heating surfaces, both evaporative and superheating. Its firebox is prismatic, quadrangular with natural circulation.
A few words about the principle of operation of the boiler:
Passing through the economizer, the drum gets feed water, through the drain pipes it goes down into the lower collectors of the pipe screens; through these pipes the water rises and, accordingly, heats up, since a torch burns inside the firebox. The water turns into a steam-water mixture, part of it goes into the remote cyclones and the other part back into the drum. In both cases, this mixture is divided into water and steam. The steam goes into the superheaters, and the water repeats its path.
11.
Cooled down flue gases(approximately 130 degrees), exit the furnace into electric precipitators. In electric precipitators, gases are purified from ash, the ash is removed to an ash dump, and the purified flue gases escape into the atmosphere. The effective degree of flue gas purification is 99.7%.
The photo shows the same electrostatic precipitators.
Passing through superheaters, the steam is heated to a temperature of 545 degrees and enters the turbine, where under its pressure the turbine generator rotor rotates and, accordingly, electricity is generated. It should be noted that in condensing power plants (GRES) the water circulation system is completely closed. All steam passing through the turbine is cooled and condensed. Turning back into liquid state, the water is reused. But in the turbines of a thermal power plant, not all the steam enters the condenser. Steam extraction is carried out - production (use of hot steam in any production) and heating (hot water supply network). This makes CHP more economically profitable, but it has its drawbacks. The disadvantage of combined heat and power plants is that they must be built close to the end user. Laying heating mains costs a lot of money.
12.
Krasnoyarsk CHPP-3 uses a direct-flow technical water supply system, which makes it possible to abandon the use of cooling towers. That is, water for cooling the condenser and used in the boiler is taken directly from the Yenisei, but before that it undergoes purification and desalting. After use, the water is returned through the canal back to the Yenisei, passing through a dissipative release system (mixing heated water with cold water in order to reduce thermal pollution of the river)
14.
Turbogenerator
I hope I was able to clearly describe the operating principle of a thermal power plant. Now a little about KrasTPP-3 itself.
Construction of the station began back in 1981, but, as happens in Russia, due to the collapse of the USSR and crises, it was not possible to build a thermal power plant on time. From 1992 to 2012, the station worked as a boiler house - it heated water, but it learned to generate electricity only on March 1 of last year.
Krasnoyarsk CHPP-3 belongs to Yenisei TGC-13. The thermal power plant employs about 560 people. Currently, Krasnoyarsk CHPP-3 provides heat supply industrial enterprises and housing and communal services sector Sovetsky district Krasnoyarsk - in particular, the microdistricts "Severny", "Vzlyotka", "Pokrovsky" and "Innokentyevsky".
17.
19.
CPU
20.
There are also 4 hot water boilers at KrasTPP-3
21.
Peephole in the firebox
23.
And this photo was taken from the roof of the power unit. The large pipe has a height of 180m, the smaller one is the pipe of the starting boiler room.
24.
Transformers
25.
A 220 kV closed gas-insulated switchgear (GRUE) is used as a switchgear at KrasTPP-3.
26.
Inside the building
28.
General form switchgear
29.
That's all. Thank you for your attention
How does a thermal power plant work? CHP units. CHP equipment. Operating principles of thermal power plants. PGU-450.
Hello, dear ladies and gentlemen!
When I studied at the Moscow Energy Institute, I lacked practice. At the institute you deal mainly with “pieces of paper”, but I rather wanted to see “pieces of iron”. It was often difficult to understand how a particular unit worked, having never seen it before. The sketches offered to students do not always allow them to understand the full picture, and few could imagine the true design, for example, steam turbine, looking only at the pictures in the book.
This page is intended to fill the existing gap and provide everyone who is interested, albeit not too detailed, but at least visual information about how the equipment of the Heat-Electro Central Plant (CHP) works “from the inside.” The article discusses a fairly new type of power unit PGU-450 for Russia, which uses a mixed cycle - steam-gas in its operation (most thermal power plants currently use only the steam cycle).
The advantage of this page is that the photographs presented on it were taken at the time of construction of the power unit, which made it possible to photograph the device of some technological equipment in disassembled form. In my opinion, this page will be most useful for students of energy specialties - for understanding the essence of the issues being studied, as well as for teachers - for using individual photographs as teaching material.
The energy source for the operation of this power unit is natural gas. When gas burns, thermal energy is released, which is then used to operate all equipment in the power unit.
In total, three energy machines operate in the power unit circuit: two gas turbines and one steam turbine. Each of the three machines is designed for a nominal electrical power output of 150 MW.
Gas turbines operate in a manner similar to jet engines.
Gas turbines require two components to operate: gas and air. Air from the street enters through air intakes. The air intakes are covered with grilles to protect the gas turbine installation from birds and any debris. They also have an anti-icing system installed that prevents ice from freezing in winter period time.
Air enters the compressor inlet gas turbine unit(axial type). After this, in compressed form, it enters the combustion chambers, where, in addition to air, natural gas is supplied. In total, each gas turbine unit has two combustion chambers. They are located on the sides. In the first photo below, the air duct has not yet been mounted, and the left combustion chamber is covered with cellophane film; in the second, a platform has already been mounted around the combustion chambers and an electric generator has been installed:
Each combustion chamber has 8 gas burners:
In the combustion chambers, the process of combustion of the gas-air mixture and the release of thermal energy occurs. This is what combustion chambers look like “from the inside” - right where the flame continuously burns. The walls of the chambers are lined with fireproof lining:
At the bottom of the combustion chamber there is a small viewing window that allows you to observe the processes occurring in the combustion chamber. The video below demonstrates the combustion process of the gas-air mixture in the combustion chamber of a gas turbine unit at the time of its startup and when operating at 30% of the rated power:
The air compressor and gas turbine share the same shaft, and part of the turbine's torque is used to drive the compressor.
The turbine produces more work than is required to drive the compressor, and the excess of this work is used to drive the "payload". An electric generator with an electrical power of 150 MW is used as such a load - it is in it that electricity is generated. In the photo below, the “gray barn” is precisely the electric generator. The electric generator is also located on the same shaft as the compressor and turbine. Everything rotates together at a frequency of 3000 rpm.
When passing gas turbine combustion products give it part of their thermal energy, but not all the energy of combustion products is used to rotate the gas turbine. A significant part of this energy cannot be used by the gas turbine, therefore the combustion products at the gas turbine outlet (exhaust gases) still carry with them a lot of heat (the temperature of the gases at the gas turbine outlet is about 500° WITH). In aircraft engines, this heat is wastefully released into the environment, but in the power unit under consideration it is used further - in the steam power cycle.To do this, exhaust gases from the gas turbine outlet are “blown” from below into the so-called. "recovery boilers" - one for each gas turbine. Two gas turbines - two waste heat boilers.
Each such boiler is a structure several floors high.
The thermal energy in these boilers exhaust gases A gas turbine is used to heat water and turn it into steam. Subsequently, this steam is used to operate in a steam turbine, but more on that later.
To heat and evaporate, water passes inside tubes with a diameter of approximately 30 mm, located horizontally, and the exhaust gases from the gas turbine “wash” these tubes from the outside. This is how heat is transferred from gases to water (steam):
Having given most of the thermal energy to steam and water, the exhaust gases end up at the top of the waste heat boiler and are removed through a chimney through the roof of the workshop:
On the outside of the building, the chimneys from two waste heat boilers converge into one vertical chimney:
The following photographs allow you to estimate the size of the chimneys. The first photo shows one of the “corners” with which the chimneys of waste heat boilers are connected to the vertical trunk of the chimney; the remaining photos show the process of installing the chimney.
But let's return to the design of waste heat boilers. The tubes through which water passes inside the boilers are divided into many sections - tube bundles, which form several sections:
1. Economizer section (which at this power unit has a special name - Gas Condensate Heater - GPC);
2. Evaporation section;
3. Steam superheating section.
The economizer section serves to heat water from a temperature of about 40°Cto a temperature close to boiling point. After this, the water enters the deaerator - a steel container, where the water parameters are maintained such that the gases dissolved in it begin to be intensively released. Gases collect at the top of the tank and are released into the atmosphere. Removing gases, especially oxygen, is necessary to prevent rapid corrosion of process equipment with which our water comes into contact.
After passing through the deaerator, the water acquires the name “feed water” and enters the inlet of the feed pumps. This is what the feed pumps looked like when they were just brought to the station (there are 3 of them in total):
Feed pumps are electrically driven (asynchronous motors are powered by a voltage of 6 kV and have a power of 1.3 MW). Between the pump itself and the electric motor there is a fluid coupling - unit,allowing you to smoothly change the speed of the pump shaft over a wide range.
The principle of operation of the fluid coupling is similar to the principle of operation of the fluid coupling in automatic transmissions of cars.
Inside there are two wheels with blades, one “sits” on the electric motor shaft, the second on the pump shaft. The space between the wheels can be filled with oil to different levels. The first wheel, rotated by the engine, creates a flow of oil that “impacts” the blades of the second wheel, drawing it into rotation. How more oil will be poured between the wheels, the better the “grip” the shafts will have between each other, and the greater mechanical power will be transmitted through a fluid coupling to the feed pump.
The oil level between the wheels is changed using the so-called. a “scoop pipe” that pumps out oil from the space between the wheels. The position of the scoop pipe is adjusted using a special actuator.
The feed pump itself is centrifugal, multi-stage. Please note that this pump develops the full steam pressure of the steam turbine and even exceeds it (by the amount of hydraulic resistance of the remaining part of the waste heat boiler, hydraulic resistance of pipelines and fittings).
It was not possible to see the design of the impellers of the new feed pump (since it was already assembled), but parts of an old feed pump of a similar design were found on the territory of the station. The pump consists of alternating rotating centrifugal wheels and fixed guide discs.
Fixed guide disc:
Impellers:
From the outlet of the feed pumps, feed water is supplied to the so-called. "drum separators" - horizontal steel containers designed to separate water and steam:
Each recovery boiler has two separator drums (4 in total per power unit). Together with the tubes of the evaporation sections inside waste heat boilers, they form circulation circuits for the steam-water mixture. It works as follows.
Water with a temperature close to the boiling point enters the tubes of the evaporation sections, flowing through which it is heated to the boiling point and then partially turns into steam. At the exit of the evaporation section we have a steam-water mixture, which enters the separator drums. Special devices are mounted inside the separator drums
Which help to separate steam from water. The steam is then supplied to the superheating section, where its temperature increases even more, and the water separated in the separator drum (separated) is mixed with feed water and again enters the evaporation section of the waste heat boiler.
After the steam superheating section, steam from one waste heat boiler is mixed with the same steam from the second waste heat boiler and supplied to the turbine. Its temperature is so high that the pipelines through which it passes, if the thermal insulation is removed from them, glow in the dark with a dark red glow. And now this steam is supplied to a steam turbine in order to give up part of its thermal energy and perform useful work.
A steam turbine has 2 cylinders - cylinder high pressure and cylinder low pressure. The low pressure cylinder is double flow. In it, the steam is divided into 2 streams operating in parallel. The cylinders contain turbine rotors. Each rotor, in turn, consists of stages - disks with blades. “Hitting” the blades, the steam causes the rotors to rotate. The photo below reflects general design steam turbine: closer to us is a high-pressure rotor, further from us is a double-flow low-pressure rotor
This is what the low pressure rotor looked like when it was just unpacked from the factory packaging. Note that it only has 4 steps (not 8):
Here's a closer look at the high pressure rotor. It has 20 steps. Also pay attention to the massive steel turbine housing, consisting of two halves - lower and upper (only the lower one is shown in the photo), and the studs with which these halves are connected to each other. In order for the housing to heat up faster during startup, but at the same time, more evenly, a steam heating system for “flanges and studs” is used - do you see a special channel around the studs? It is through it that a special stream of steam passes to warm up the turbine housing during its startup.
In order for the steam to “hit” the rotor blades and force them to rotate, this steam must first be directed and accelerated in in the right direction. For this purpose the so-called nozzle grilles - fixed sections with fixed blades, placed between the rotating rotor disks. The nozzle grilles DO NOT rotate - they are NOT mobile, and serve only to direct and accelerate the steam in the desired direction. In the photo below, steam passes “from behind these blades towards us” and “spins” around the axis of the turbine counterclockwise. Further, “hitting” the rotating blades of the rotor disks, which are located immediately behind the nozzle grille, the steam transfers its “rotation” to the turbine rotor.
In the photo below you can see parts of the nozzle grilles prepared for installation
And in these photographs - bottom part turbine housing with halves of nozzle grids already installed in it:
After this, the rotor is “put” into the housing, the upper halves of the nozzle grilles are mounted, then the upper part of the housing, then various pipelines, thermal insulation and casing:
After passing through the turbine, the steam enters the condensers. This turbine has two condensers - according to the number of flows in the low-pressure cylinder. Look at the photo below. It clearly shows the lower part of the steam turbine housing. Note the rectangular parts of the low-pressure cylinder housing, covered with wooden panels on top. These are steam turbine exhausts and condenser inlets.
When the steam turbine housing is fully assembled, a space is formed at the outlets of the low-pressure cylinder, the pressure in which during operation of the steam turbine is approximately 20 times lower than atmospheric pressure, therefore the low-pressure cylinder housing is designed not to resist pressure from the inside, but to resist pressure from the outside - i.e. e. atmospheric pressure air. The condensers themselves are located under the low pressure cylinder. In the photo below, these are rectangular containers with two hatches on each.
The condenser is designed similar to a waste heat boiler. Inside it there are many tubes with a diameter of approximately 30mm. If we open one of the two hatches of each condenser and look inside, we will see "tube sheets":
Cooling water, called process water, flows through these tubes. Steam from the exhaust of a steam turbine ends up in the space between the tubes outside them (behind the tube sheet in the photo above), and, giving off residual heat to the process water through the walls of the tubes, condenses on their surface. The steam condensate flows down, accumulates in condensate collectors (at the bottom of the condensers), and then enters the inlet of the condensate pumps. Each condensate pump (there are 5 in total) is driven by a three-phase asynchronous electric motor, designed for a voltage of 6 kV.
From the output of the condensate pumps, water (condensate) again enters the input of the economizer sections of waste heat boilers and, thus, the steam power cycle is closed. The entire system is almost sealed and water, which is the working fluid, is repeatedly converted into steam in waste heat boilers, in the form of steam it does work in the turbine to be converted back into water in the turbine condensers, etc.
This water (in the form of water or steam) is constantly in contact with the internal parts of the process equipment, and in order not to cause rapid corrosion and wear, it is chemically prepared in a special way.
But let's return to the steam turbine condensers.
Process water heated in the tubes of steam turbine condensers, according to underground pipelines technical water supply is removed from the workshop and supplied to cooling towers - in order to release the heat taken from the steam from the turbine to the surrounding atmosphere. The photographs below show the design of the cooling tower erected for our power unit. The principle of its operation is based on the spraying of warm technical water inside the cooling tower using showering devices (from the word “shower”). Drops of water fall down and give up their heat to the air inside the cooling tower. The heated air rises up, and in its place comes from the bottom of the cooling tower cold air from the street.
This is what the cooling tower looks like at its base. It is through the “gap” at the bottom of the cooling tower that cold air comes in to cool the process water
At the bottom of the cooling tower there is a drainage basin where drops of technical water fall and collect, released from the showering devices and giving up their heat to the air. Above the pool there is a system of distribution pipes through which warm process water is supplied to showering devices
The space above and below the showering devices is filled with special padding made from plastic blinds. The lower louvres are designed to more evenly distribute “rain” over the area of the cooling tower, and the upper louvres are designed to catch small droplets of water and prevent excessive carryover of process water along with the air through the top of the cooling tower. However, at the time the photographs presented were taken, the plastic blinds had not yet been installed.
Bo" The largest part of the cooling tower is not filled with anything and is intended only to create draft (heated air rises upward). If we stand above the distribution pipelines, we will see that there is nothing above and the rest of the cooling tower is empty
The following video conveys the impressions of being inside the cooling tower
At the time when the photographs of this page were taken, the cooling tower built for the new power unit was not yet operational. However, on the territory of this thermal power plant there were other cooling towers that were operating, which made it possible to capture a similar cooling tower in operation. Steel louvres at the bottom of the cooling tower are designed to regulate the flow of cold air and prevent overcooling of process water in winter.
The process water, cooled and collected in the cooling tower basin, is again supplied to the inlet of the steam turbine condenser tubes to remove the steam new portion heat, etc. In addition, process water is used to cool other process equipment, for example, electric generators.
The following video shows how process water is cooled in a cooling tower.
Since process water is in direct contact with the surrounding air, dust, sand, grass and other dirt get into it. Therefore, at the entrance of this water to the workshop, on the inlet pipeline of technical water, a self-cleaning filter is installed. This filter consists of several sections mounted on a rotating wheel. From time to time, a reverse flow of water is organized through one of the sections to wash it. Then the wheel with sections turns, and washing of the next section begins, etc.
This is what this self-cleaning filter looks like from inside the service water pipeline:
And this is from the outside (the drive motor has not yet been mounted):
Here we should make a digression and say that the installation of all technological equipment in the turbine shop is carried out using two overhead cranes. Each crane has three separate winches designed to handle loads of different weights.
Now I would like to talk a little about the electrical part of this power unit.
Electricity is generated using three electric generators driven by two gas and one steam turbines. Some of the equipment for the installation of the power unit was brought by road, and some by rail. A railway was laid directly into the turbine shop, along which large-sized equipment was transported during the construction of the power unit.
The photo below shows the process of delivering the stator of one of the electric generators. Let me remind you that each electric generator has a rated electrical power of 150 MW. Note that the railway platform on which the generator stator was transported has 16 axles (32 wheels).
The railway has a slight rounding at the entrance to the workshop, and given that the wheels of each wheel pair are rigidly fixed to their axles, when moving on a rounded section railway one of the wheels of each wheel pair is forced to slip (since the rails have different lengths at the curve). The video below shows how this happened when the platform with the stator of an electric generator was moving. Pay attention to how the sand bounces on the sleepers as the wheels slip along the rails.
Due to their large mass, the installation of electric generator stators was carried out using both overhead cranes:
The photo below shows internal view stator of one of the electric generators:
And this is how the installation of electric generator rotors was carried out:
Output voltage generators is about 20 kV. Output current - thousands of amperes. This electricity is removed from the turbine shop and supplied to step-up transformers located outside the building. To transfer electricity from electric generators to step-up transformers, the following electrical wires are used (the current flows through a central aluminum pipe):
To measure the current in these “wires” the following current transformers are used (in the third photo above the same current transformer is standing vertically):
The photo below shows one of the step-up transformers. Output voltage - 220 kV. From their outputs, electricity is supplied to the power grid.
In addition to electrical energy, the CHP also produces thermal energy used for heating and hot water supply to nearby areas. To do this, steam extraction is carried out in the steam turbine, i.e., part of the steam is removed from the turbine before reaching the condenser. This still quite hot steam enters the network heaters. A network heater is a heat exchanger. It is very similar in design to a steam turbine condenser. The difference is that it is not process water that flows in the tubes, but network water. There are two network heaters at the power unit. Let's look again at the photo with the capacitors of the old turbine. Rectangular containers are capacitors, and “round” ones are precisely network heaters. Let me remind you that all this is located under the steam turbine.
The network water heated in the tubes of network heaters is supplied through underground pipelines of network water into the heating network. Having heated the buildings in the areas located around the thermal power plant and given up its heat to them, the network water returns to the station to be heated again in network heaters, etc.
The operation of the entire power unit is controlled by the automated process control system "Ovation" of the American corporation "Emerson"
And here’s what the cable mezzanine, located under the automated process control system room, looks like. Through these cables, the automated process control system receives signals from many sensors, and also sends signals to actuators.
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Once, when we were entering the glorious city of Cheboksary, with east direction my wife noticed two huge towers standing along the highway. "And what is it?" – she asked. Since I absolutely did not want to show my wife my ignorance, I dug a little into my memory and came out victoriously: “These are cooling towers, don’t you know?” She was a little embarrassed: “What are they for?” “Well, there’s something there to cool, it seems.” "And what?". Then I got embarrassed because I didn’t know how to get out of it any further.
This question may remain forever in the memory without an answer, but miracles happen. A few months after this incident, I see a post in my friend feed about a recruitment of bloggers who want to visit the Cheboksary CHPP-2, the same one that we saw from the road. You have to suddenly change all your plans; missing such a chance would be unforgivable!
So what is CHP?
According to Wikipedia, CHP - short for combined heat and power plant - is a type of thermal station that produces not only electricity, but also a source of heat, in the form of steam or hot water.
I’ll tell you how everything works below, but here you can see a couple of simplified diagrams of the station’s operation.
So, it all starts with water. Since water (and steam, as its derivative) at a thermal power plant is the main coolant, before it enters the boiler, it must first be prepared. In order to prevent scale from forming in boilers, at the first stage, the water must be softened, and at the second, it must be cleaned of all kinds of impurities and inclusions.
All this happens on the territory of the chemical workshop, in which all these containers and vessels are located.
Water is pumped by huge pumps.
The work of the workshop is controlled from here.
There are a lot of buttons around...
Sensors...
And also completely incomprehensible elements...
The quality of the water is checked in the laboratory. Everything is serious here...
The water obtained here will be called “Clean Water” in the future.
So, we've sorted out the water, now we need fuel. Usually it is gas, fuel oil or coal. At the Cheboksary CHPP-2, the main type of fuel is gas supplied through the Urengoy – Pomary – Uzhgorod gas pipeline. Many stations have a fuel preparation point. Here, natural gas, like water, is purified from mechanical impurities, hydrogen sulfide and carbon dioxide.
The thermal power plant is a strategic facility, operating 24 hours a day and 365 days a year. Therefore, here everywhere, and for everything, there is a reserve. Fuel is no exception. In the absence of natural gas, our station can operate on fuel oil, which is stored in huge tanks located across the road.
Now we have Clean water and prepared fuel. The next point of our journey is the boiler-turbine shop.
It consists of two sections. The first contains boilers. No not like this. The first contains BOILERS. To write it differently, a hand doesn’t rise, each one is the size of a twelve-story building. There are five of them at CHPP-2 in total.
This is the heart of the power plant and where most of the action takes place. The gas entering the boiler burns, releasing a crazy amount of energy. “Clean water” is also supplied here. After heating, it turns into steam, more precisely into superheated steam, having an outlet temperature of 560 degrees and a pressure of 140 atmospheres. We will also call it “Clean Steam”, because it is formed from prepared water.
In addition to steam, we also have exhaust at the exit. At maximum power, all five boilers consume almost 60 cubic meters of natural gas per second! To remove combustion products, you need a non-childish “smoke” pipe. And there is one like this too.
The pipe can be seen from almost any area of the city, given the height of 250 meters. I suspect that this is the tallest building in Cheboksary.
Nearby there is a slightly smaller pipe. Reserve again.
If the thermal power plant operates on coal, additional exhaust cleaning is necessary. But in our case this is not required, since natural gas is used as fuel.
In the second department of the boiler-turbine shop there are installations that generate electricity.
There are four of them installed in the turbine hall of the Cheboksary CHPP-2, with a total capacity of 460 MW (megawatt). This is where superheated steam from the boiler room is supplied. It is directed under enormous pressure onto the turbine blades, causing the thirty-ton rotor to rotate at a speed of 3000 rpm.
The installation consists of two parts: the turbine itself, and a generator that generates electricity.
And this is what the turbine rotor looks like.
Sensors and pressure gauges are everywhere.
Both turbines and boilers, in case emergency situation can be stopped instantly. For this, there are special valves that can shut off the supply of steam or fuel in a fraction of a second.
I wonder if there is such a thing as an industrial landscape, or an industrial portrait? There is beauty here.
There is a terrible noise in the room, and in order to hear your neighbor you have to strain your ears. Plus it's very hot. I want to take off my helmet and strip down to my T-shirt, but I can’t do that. For safety reasons, short-sleeved clothing is prohibited at the thermal power plant; there are too many hot pipes.
Most of the time the workshop is empty; people appear here once every two hours, during their rounds. And the operation of the equipment is controlled from the Main Control Panel (Group Control Panels for Boilers and Turbines).
This is what it looks like workplace duty officer
There are hundreds of buttons around.
And dozens of sensors.
Some are mechanical, some are electronic.
This is our excursion, and people are working.
In total, after the boiler-turbine shop, at the output we have electricity and steam that has partially cooled and lost some of its pressure. Electricity seems to be easier. The output voltage from different generators can be from 10 to 18 kV (kilovolts). With the help of block transformers, it increases to 110 kV, and then electricity can be transmitted over long distances using power lines (power lines).
It is not profitable to release the remaining “Pure Steam” to the side. Since it is formed from " Clean water", the production of which is a rather complex and costly process, it is more expedient to cool it and return it back to the boiler. And so on vicious circle. But with its help and with the help of heat exchangers, you can heat water or produce secondary steam, which you can safely sell to third-party consumers.
In general, this is how you and I get heat and electricity into our homes, having the usual comfort and coziness.
Oh yes. But why are cooling towers needed anyway?
An electrical station is a set of equipment designed to convert the energy of any natural source into electricity or heat. There are several varieties of such objects. For example, thermal power plants are often used to generate electricity and heat.
Definition
A thermal power plant is an electric power plant that uses any fossil fuel as an energy source. The latter can be used, for example, oil, gas, coal. On 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 (transcript from Its abbreviation looks like “thermal power plant”), among other things, a complex with a fairly high efficiency. Depending on the type of turbines used, this indicator at stations similar type can be equal to 30 - 70%.
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:
- steam-gas.
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 thatpart of the thermal energy it generates goes to boilers installed in rooms 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, hydroelectric power stations are fundamentally different from state regional power plants. Both of these types of stations are built on rivers. However, at hydroelectric power plants, 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 supply sources should be carefully protected from the ingress of wastewater;
- water treatment systems at stations should be equippedwaste-free.
Operating principle of thermal power plants
TPP is a power plant, on which turbines can be used different 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. Oxidizing agent in in this case heated air emerges.
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.
Deae The purified water is heated and supplied to the boiler.
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.
Disadvantages of thermal power plants
Of course, such stations have not only advantages. They also have a number of disadvantages. Thermal power plants are complexes that, unfortunately, heavily pollute the environment. Stations of this type can simply release great amount soot and smoke. Also, the disadvantages of thermal power plants include high operating costs compared to hydroelectric power plants. In addition, all types of fuel used at such stations are considered irreplaceable natural resources.
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 do not rotate 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.
Examples of stations
So, any object can be considered quite productive and, to some extent, even universal. I am a thermal power plant, a power plant. Examples We present 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 Volgograd region and can run 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.
Instead of a conclusion
Thus, we found out what thermal power plants are and what types of such objects exist. The first complex of this type was built a long time ago - in 1882 in New York. A year later, such a system started working in Russia - in St. Petersburg. Today, thermal power plants are a type of power plant, which account for about 75% of all electricity generated in the world. And apparently, despite a number of disadvantages, stations of this type will provide the population with electricity and heat for a long time. After all, the advantages of such complexes are an order of magnitude greater than the disadvantages.
