Once, when we were driving into the glorious city of Cheboksary, from the east, 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 ignorance to my wife, I dug a little in my memory and issued a victorious one: “These are cooling towers, don’t you know?”. She was a little embarrassed: “What are they for?” “Well, something to cool there, it seems.” "And what?". Then I was embarrassed, because I did not know at all how to get out further.
Maybe this question has remained forever in the memory without an answer, but miracles do happen. A few months after this incident, I see a post in my friend feed about the recruitment of bloggers who want to visit the Cheboksary CHPP-2, the same one that we saw from the road. Having to drastically change all your plans, it would be unforgivable to miss such a chance!
So what is CHP?
According to Wikipedia CHP - short for combined heat and power plant - is a type of thermal power plant that produces not only electricity, but also a source of heat, in the form of steam or hot water.
I will tell about how everything works below, and here you can see a couple of simplified schemes for the operation of the station.
So, everything starts with water. Since water (and steam, as its derivative) is the main heat carrier at the CHP, before it enters the boiler, it must first be prepared. In order to prevent the formation of scale in the 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 takes place 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.
Lots of buttons around...
Sensors…
And also completely obscure elements ...
Water quality is tested in the laboratory. Everything is serious here...
The water obtained here, in the future, we will call "Pure Water".
So, we figured out the water, now we need fuel. Usually it is gas, fuel oil or coal. At Cheboksary CHPP-2, the main type of fuel is gas supplied through the main gas pipeline Urengoy - Pomary - Uzhgorod. At many stations there is a fuel preparation point. Here, natural gas, as well as water, is purified from mechanical impurities, hydrogen sulfide and carbon dioxide.
The CHPP is a strategic facility, operating 24 hours a day, 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 run 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 and turbine shop.
It consists of two departments. The first one contains boilers. No not like this. In the first one there are BOILERS. To write differently, the hand does not rise, each, with a twelve-story building. In total, there are five of them at CHPP-2.
This is the heart of the CHP plant, and here the main action takes place. The gas entering the boiler burns out, releasing a crazy amount of energy. This is where Pure Water comes in. 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 "Pure 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 the products of combustion, you need a non-childish "smoke" pipe. And there is one 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 is a slightly smaller pipe. Reserve again.
If the CHP plant is coal-fired, additional cleaning exhaust. But in our case, this is not required, since natural gas is used as fuel.
In the second section of the boiler and turbine shop there are installations that generate electricity.
Four of them are installed in the engine room of the Cheboksary CHPP-2, with a total capacity of 460 MW (megawatts). It is here that superheated steam from the boiler room is supplied. He, under huge pressure, is sent to the turbine blades, forcing 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 here is what the turbine rotor looks like.
Sensors and gauges are everywhere.
Both turbines and boilers can be stopped instantly in case of an emergency. For this, there are special valves that can shut off the supply of steam or fuel in a fraction of a second.
Interestingly, is there such a thing as an industrial landscape, or an industrial portrait? It has its own beauty.
There is a terrible noise in the room, and in order to hear a neighbor, you have to strain your hearing a lot. Besides, 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 CHP plant, there are too many hot pipes.
Most of the time, the workshop is empty, people appear here once every two hours, during a round. And the operation of the equipment is controlled from the Main Control Board (Group Control Panels for Boilers and Turbines).
This is what it looks like workplace on duty.
There are hundreds of buttons around.
And dozens of sensors.
Some are mechanical and some are electronic.
This is our excursion, and people are working.
In total, after the boiler and turbine shop, at the output we have electricity and steam that has partially cooled down and lost part of its pressure. With electricity, it seems to be easier. At the output from different generators, the voltage can be from 10 to 18 kV (kilovolt). With the help of block transformers, it rises to 110 kV, and then electricity can be transmitted to long distances with the help of power lines (power lines).
It is unprofitable to release the remaining “Clean Steam” to the side. Since it is formed from pure water”, the production of which is a rather complicated and costly process, it is more expedient to cool it and return it to the boiler. And so in a vicious circle. But with its help and with the help of heat exchangers, you can heat water or produce secondary steam, which can be safely sold to third-party consumers.
In general, this is how we get heat and electricity into our homes, having the usual comfort and coziness.
Oh yes. Why are cooling towers needed anyway?
Supplying the population with heat and electricity is one of the main tasks of the state. In addition, without the generation of electricity, it is impossible to imagine a developed manufacturing and processing industry, without which the country's economy cannot exist in principle.
One of the ways to solve the problem of energy shortage is the construction of a thermal power plant. The decoding of this term is quite simple: this is the so-called combined heat and power plant, which is one of the most common types of thermal power plants. In our country, they are very common, as they run on organic fossil fuels (coal), the characteristics of which are subject to very modest requirements.
Peculiarities
That's what CHP is. Deciphering the concept is already familiar to you. But what are the features of this type of power plant? After all, it is no coincidence that they are singled out in a separate category!?
The fact is that they produce not only electricity, but also heat, which is supplied to consumers in the form of hot water and steam. It should be noted that electricity is a by-product, since the steam that is supplied to the heating systems first rotates the turbines of the generators. The combination of two enterprises (boiler house and power plant) is good because it is possible to significantly reduce fuel consumption.
However, this also leads to a rather insignificant "distribution area" of CHP. The decoding is simple: since not only electricity is supplied from the station, which can be transported thousands of kilometers with minimal losses, but also a heated coolant, they cannot be located at a considerable distance from the settlement. It is not surprising that almost all thermal power plants are built in the immediate vicinity of the cities, the inhabitants of which they heat and light.
Ecological significance
Due to the fact that during the construction of such a power plant it is possible to get rid of many old city boiler houses, which play an extremely negative role in the ecological state of the area (a huge amount of soot), the air purity in the city can sometimes be increased by an order of magnitude. In addition, new thermal power plants make it possible to eliminate rubbish piles in city dumps.
The latest cleaning equipment allows you to effectively clean the emission, and the energy efficiency of such a solution turns out to be extremely high. Thus, the release of energy from burning a ton of oil is identical to its volume, which is released when recycling two tons of plastic. And this "good" will be enough for decades to come!
Most often, the construction of a CHP involves the use of fossil fuels, as we have already discussed above. However, in recent years, it is planned to create which will be mounted in the conditions of hard-to-reach regions of the Far North. Since the supply of fuel there is extremely difficult, nuclear power is the only reliable and permanent source of energy.
What are they like?
There are thermal power plants (photos of which are in the article) industrial and "household", heating. As you might guess from the name, industrial power plants provide electricity and heat to large manufacturing enterprises.
Often they are built at the stage of plant construction, making up a single infrastructure with it. Accordingly, "domestic" varieties are being built near the sleeping districts of the city. In industrial it is transmitted in the form of hot steam (no more than 4-5 km), in the case of heating - with hot water (20-30 km).
Information about station equipment
The main equipment of these enterprises are turbine units, which convert mechanical energy into electricity, and boilers, responsible for generating steam, which rotates the flywheels of generators. The turbine unit includes both the turbine itself and the synchronous generator. Pipes with a back pressure of 0.7–1.5 MN/m2 are installed in those CHP plants that supply heat and energy. industrial facilities. Models with a pressure of 0.05-0.25 MN/m2 serve to provide domestic consumers.
Efficiency issues
In principle, all generated heat can be fully utilized. That's just the amount of electricity that is generated at the CHP (the decoding of this term you already know) directly depends on the heat load. Simply put, in the spring and summer, its production decreases almost to zero. Thus, backpressure installations are used only to supply industrial capacities, in which the consumption value is more or less uniform throughout the entire period.
Condensing units
In this case, only the so-called “removal steam” is used to supply consumers with heat, and all the rest of the heat is often simply lost, dissipating in the environment. In order to reduce energy losses, such CHP plants must operate with minimal heat output to the condensing unit.
However, since the times of the USSR, such plants have been built in which a hybrid mode is structurally provided: they can operate as conventional condensing CHP plants, but their turbine generator fully allows operation in the backpressure mode.
Universal varieties
It is not surprising that it is installations with steam condensation that have received the maximum distribution due to their versatility. So, only they make it possible to almost independently regulate the electrical and thermal load. Even if no heat load is expected at all (in the event of a particularly hot summer), the population will be supplied with electricity according to the previous schedule (Western CHPP in St. Petersburg).
"Thermal" types of CHP
As you can already understand, heat generation at such power plants is extremely uneven throughout the year. Ideally, about 50% of hot water or steam is used to heat consumers, and the rest of the coolant is used to generate electricity. This is how the Yugo-Zapadnaya CHP works in the Northern Capital.
Heat release in most cases is carried out according to two schemes. If an open version is used, then the hot steam from the turbines goes directly to the consumers. If a closed scheme of operation was chosen, the coolant is supplied after passing through the heat exchangers. The choice of scheme is determined based on many factors. First of all, the distance from the object provided with heat and electricity, the population and the season are taken into account. Thus, the Yugo-Zapadnaya CHPP in St. Petersburg operates according to a closed scheme, as it provides greater efficiency.
Characteristics of the fuel used
Can be used solid, liquid and Since thermal power plants are often built in close proximity to large settlements and cities, it is often necessary to use quite valuable types of it, gas and fuel oil. The use of coal and garbage as such in our country is quite limited, since not all stations have modern efficient air-cleaning equipment.
Special particulate traps are used to clean the exhaust of installations. To disperse solid particles in sufficiently high layers of the atmosphere, they build pipes 200-250 meters high. As a rule, all combined heat and power plants (CHP) are located at a sufficiently large distance from water supply sources (rivers and reservoirs). Therefore, artificial systems are used, which include cooling towers. Direct-flow water supply is extremely rare, in very specific conditions.
Features of gas stations
Gas-fired thermal power plants stand apart. Heat supply to consumers is carried out not only due to the energy that is generated during combustion, but also from the utilization of the heat of the gases that are formed in this case. The efficiency of such installations is extremely high. In some cases, nuclear power plants can also be used as CHPs. This is especially common in some Arab countries.
There, these stations play two roles at once: they provide the population with electricity and technical water, as they simultaneously perform the functions. Now let's look at the main thermal power plants in our country and neighboring countries.
Yugo-Zapadnaya, St. Petersburg
In our country, the Zapadnaya CHPP, which is located in St. Petersburg, is famous. Registered as OAO Yugo-Zapadnaya CHPP. The construction of this modern facility pursued several functions at once:
- Compensation for the severe shortage of thermal energy, which prevented the intensification of the housing construction program.
- Improving the reliability and energy efficiency of the city system as a whole, since St. Petersburg had problems with this aspect. CHP allowed to partially solve this problem.
But this station is also known for being one of the first in Russia to meet the strictest environmental requirements. The city government allocated an area of more than 20 hectares for the new enterprise. The fact is that a reserve area left over from the Kirovsky district was allotted for construction. In those parts there was an old ash collector from CHPP-14, and therefore the area was not suitable for housing construction, but it was extremely well located.
The launch took place at the end of 2010, and almost the entire leadership of the city was present at the ceremony. Two newest automatic boiler plants were put into operation.
Murmansk
The city of Murmansk is known as the base of our fleet on the Baltic Sea. But he is also characterized by extreme severity. climatic conditions, which imposes certain requirements on its energy system. It is not surprising that the Murmansk CHPP is in many ways a completely unique technical facility, even on a national scale.
It was put into operation in 1934, and since then continues to regularly supply the residents of the city with heat and electricity. However, in the first five years, the Murmanskaya CHPP was an ordinary power plant. The first 1150 meters of the heating main were laid only in 1939. The point is the launched Nizhne-Tulomskaya hydroelectric power station, which almost completely covered the city's needs for electricity, and therefore it became possible to free up part of the heat output for heating city houses.
The station is characterized by the fact that it operates in a balanced mode throughout the year, since its thermal and "energy" outputs are approximately equal. However, in the conditions of the polar night, the thermal power plant at some peak moments begins to use most fuel for generating electricity.
Novopolotsk station, Belarus
The design and construction of this facility began in August 1957. The new Novopolotsk CHPP was supposed to solve the problem of not only supplying the city with heat, but also providing electricity to an oil refinery under construction in the same area. In March 1958, the project was finally signed, approved and approved.
The first stage was put into operation in 1966. The second was launched in 1977. At the same time, the Novopolotsk CHPP was modernized for the first time, its peak capacity was increased to 505 MW, and a little later, the third stage of construction was laid, completed in 1982. In 1994, the station was switched to liquefied natural gas.
To date, about 50 million US dollars have already been invested in the modernization of the enterprise. Thanks to such an impressive cash injection, the enterprise was not only fully converted to gas, but also received a huge amount of completely new equipment, which will allow the station to serve for decades to come.
conclusions
Oddly enough, but today it is the outdated CHPPs that are truly universal and promising stations. Using modern neutralizers and filters, it is possible to heat water by burning almost all the garbage that the settlement produces. This achieves a triple benefit:
- Landfills are unloaded and cleared.
- The city receives cheap electricity.
- The problem with heating is solved.
In addition, in coastal areas it is quite possible to build thermal power plants, which will also be desalination plants. sea water. Such a liquid is quite suitable for irrigation, for livestock complexes and industrial enterprises. In a word, real technology future!
The blades of the impellers are clearly visible in this steam turbine.
Thermal power plant (CHP) uses the energy released by burning fossil fuels - coal, oil and natural gas - to turn water into steam high pressure. This steam, which has a pressure of about 240 kilograms per square centimeter and a temperature of 524°C (1000°F), drives a turbine. The turbine spins a giant magnet inside a generator that generates electricity.
Modern thermal power plants convert about 40 percent of the heat released during the combustion of fuel into electricity, the rest is dumped into environment. In Europe, many thermal power plants use waste heat to heat nearby homes and businesses. The combined generation of heat and electricity increases the energy efficiency of the power plant by up to 80 percent.
Steam turbine plant with electric generator
A typical steam turbine contains two sets of blades. High-pressure steam coming directly from the boiler enters the flow path of the turbine and rotates the impellers with the first group of blades. Then the steam is heated in the superheater and again enters the turbine flow path to rotate the impellers with the second group of blades, which operate at a lower steam pressure.
Sectional view
A typical generator in a thermal power plant (CHP) is driven directly by a steam turbine that rotates at 3,000 revolutions per minute. In generators of this type, the magnet, which is also called the rotor, rotates, and the windings (stator) are stationary. The cooling system prevents the generator from overheating.
Steam power generation
In a thermal power plant, the fuel is burned in a boiler to form a high-temperature flame. Water passes through the tubes through the flame, heats up and turns into high pressure steam. The steam drives the turbine, producing mechanical energy, which the generator converts into electricity. After leaving the turbine, the steam enters the condenser, where it washes the tubes with cold running water, and as a result turns back into a liquid.
Oil, coal or gas boiler
Inside the boiler
The boiler is filled with intricately curved tubes through which heated water passes. The complex configuration of the tubes allows you to significantly increase the amount of heat transferred to the water and, due to this, produce much more steam.
INTRODUCTION four
1 CHP POWER PLANTS.. 5
1.1 general characteristics. 5
1.2 Schematic diagram of CHP.. 10
1.3 The principle of operation of CHP. eleven
1.4 Heat consumption and efficiency of CHP…………………………………………………..15
2 COMPARISON OF RUSSIAN CHPPS WITH FOREIGN .. 17
2.1 China. 17
2.2 Japan. eighteen
2.3 India. 19
2.4 UK. twenty
CONCLUSION. 22
REFERENCES.. 23
INTRODUCTION
CHP is the main production link in the district heating system. The construction of a thermal power plant is one of the main directions in the development of the energy economy in the USSR and other socialist countries. In the capitalist countries, thermal power plants are of limited distribution (mainly industrial thermal power plants).
Combined heat and power plants (CHP) are power plants with combined generation of electricity and heat. They are characterized by the fact that the heat of each kilogram of steam taken from the turbine is used partly to generate electrical energy, and then to consumers of steam and hot water.
CHP is designed for centralized supply of industrial enterprises and cities with heat and electricity.
Technically and economically justified production planning at CHP plants allows achieving the highest operational performance with minimal cost all types of production resources, since at the CHP the heat of the steam "spent" in the turbines is used for the needs of production, heating and hot water supply.
CHP POWER PLANTS
A combined heat and power plant is a power plant that generates electrical energy by converting the chemical energy of the fuel into mechanical energy of rotation of the shaft of the electric generator.
general characteristics
Combined heat and power plant - thermal power plant , generating not only electrical energy, but also heat supplied to consumers in the form of steam and hot water. The use for practical purposes of the waste heat of engines rotating electrical generators is distinctive feature CHP and is called Heat supply. The combined production of two types of energy contributes to a more economical use of fuel compared to the separate generation of electricity at condensing power plants and thermal energy at local boiler plants. Replacing local boiler houses that use fuel irrationally and pollute the atmosphere of cities and towns with a centralized heating system contributes not only to significant fuel savings, but also to an increase in the purity of the air basin , improvement of the sanitary condition of populated areas.
The initial source of energy at CHPPs is organic fuel (at steam turbine and gas turbine CHPPs) or nuclear fuel (at planned nuclear CHPPs). Steam-turbine CHPPs operating on fossil fuels (1976) are predominantly distributed ( rice. one), which, along with condensing power plants, are the main type of thermal steam turbine power plants (TPES). There are industrial type CHP plants - for supplying heat to industrial enterprises, and heating type- for heating residential and public buildings, as well as to supply them hot water. Heat from industrial CHP plants is transferred over a distance of up to several km(mainly in the form of steam heat), from heating - at a distance of up to 20-30 km(in the form of hot water heat).
The main equipment of steam turbine CHPPs is turbine units that convert the energy of the working substance (steam) into electrical energy, and boiler units , generating steam for turbines. The turbine unit consists of a steam turbine and Synchronous generator. Steam turbines used in CHP plants are called combined heat and power turbines (CTs). Among them, TT is distinguished: with a back pressure, usually equal to 0.7-1.5 Mn/m 2 (installed at CHPPs supplying industrial enterprises with steam); with condensation and steam extraction under pressure 0.7-1.5 Mn/m 2 (for industrial consumers) and 0.05-0.25 Mn/m 2 (for household consumers); with condensation and steam extraction (heating) under pressure 0.05-0.25 Mn/m 2 .
Waste heat from backpressure CTs can be fully utilized. However, the electric power developed by such turbines depends directly on the magnitude of the thermal load, and in the absence of the latter (as, for example, happens in the summer at heating CHP plants), they do not produce electric power. Therefore, CTs with backpressure are used only if there is a sufficiently uniform heat load provided for the entire duration of the operation of the CHP (that is, mainly at industrial CHPs).
For heat pumps with condensation and steam extraction, only extraction steam is used to supply heat to consumers, and the heat of the condensing steam flow is given off in the condenser to the cooling water and is lost. To reduce heat losses, such CTs should operate most of the time according to the "thermal" schedule, that is, with a minimum "ventilation" passage of steam into the condenser. In the USSR, HPs with condensation and steam extraction were developed and built, in which the use of condensation heat is envisaged: such HPs under conditions of sufficient heat load can operate as HPs with backpressure. CTs with condensation and steam extraction are predominantly used at CHPPs as universal ones in terms of possible operating modes. Their use allows you to adjust the thermal and electrical loads almost independently; in a particular case, with reduced thermal loads or in their absence, the CHP plant can operate according to the “electrical” schedule, with the necessary, full or almost full electrical power.
The electric power of heating turbine units (Unlike condensing units) is preferably chosen not according to a given power scale, but according to the amount of fresh steam consumed by them. Therefore, in the USSR, large cogeneration turbine units are unified precisely according to this parameter. Thus, R-100 turbine units with backpressure, PT-135 with industrial and heating extractions, and T-175 with heating extractions have the same flow rate of live steam (about 750 t/h), but different electric power (respectively 100, 135 and 175 MW). Boilers generating steam for such turbines have the same capacity (about 800 t/h). Such unification makes it possible to use turbine units of various types with the same thermal equipment of boilers and turbines at one CHPP. In the USSR, the boiler units used to work at TPPs for various purposes were also unified. So, boiler units with a steam capacity of 1000 t/h used to supply steam as condensing turbines for 300 MW, and the largest TTs in the world at 250 MW.
Thermal load at heating CHPPs is uneven throughout the year. In order to reduce the cost of the main power equipment, part of the heat (40-50%) during periods of increased load is supplied to consumers from peak hot water boilers. The share of heat released by the main power equipment at the highest load determines the value of the CHP heat supply coefficient (usually equal to 0.5-0.6). Similarly, it is possible to cover the peaks of the thermal (steam) industrial load (about 10-20% of the maximum) with low-pressure peak steam boilers. Heat release can be carried out according to two schemes ( rice. 2). At open circuit steam from the turbines is sent directly to consumers. With a closed circuit, heat is supplied to the coolant (steam, water) transported to consumers through heat exchangers (steam and steam-water). The choice of scheme is determined to a large extent by the water regime of the CHPP.
Thermal power plants use solid, liquid or gaseous fuels. Due to the greater proximity of thermal power plants to populated areas, they use more valuable fuel, less polluting the atmosphere with solid emissions - fuel oil and gas - more widely (compared to the state district power plant). To protect the air basin from pollution with solid particles, ash collectors are used (as at the state district power station). , for dispersion in the atmosphere of solid particles, sulfur and nitrogen oxides, chimneys are built up to 200-250 m. CHP plants built near heat consumers are usually separated from water supply sources at a considerable distance. Therefore, most thermal power plants use a circulating water supply system with artificial coolers - cooling towers. Direct-flow water supply at CHP plants is rare.
At gas turbine CHP plants, gas turbines are used to drive electric generators. The heat supply to consumers is carried out due to the heat taken from the cooling of the air compressed by the compressors of the gas turbine plant, and the heat of the gases exhausted in the turbine. Combined-cycle power plants (equipped with steam turbine and gas turbine units) and nuclear power plants can also operate as CHPPs.
Rice. one. General form combined heat and power plants.
Rice. 2. The simplest schemes of combined heat and power plants with various turbines and various schemes steam release: a - turbine with back pressure and steam extraction, heat release - according to an open scheme; b - condensing turbine with steam extraction, heat supply - according to open and closed schemes; PC - steam boiler; PP - superheater; PT - steam turbine; G - electric generator; K - capacitor; P - regulated production steam extraction for the technological needs of the industry; T - adjustable heat extraction for heating; TP - heat consumer; FROM - heating load; KN and PN - condensate and feed pumps; LDPE and HDPE - high and low pressure heaters; D - deaerator; PB - feed water tank; SP - network heater; CH - network pump.
Schematic diagram of CHP
Rice. 3. Schematic diagram of CHP.
Unlike CPP, CHP produces and distributes to consumers not only electrical, but also thermal energy in the form of hot water and steam.
To supply hot water, network heaters (boilers) are used, in which water is heated by steam from the turbine heat extraction to the required temperature. Water in network heaters is called network. After cooling at the consumers, the network water is again pumped to the network heaters. Boiler condensate is pumped to the deaerator.
Steam given to production is used by plant consumers for various purposes. The nature of this use depends on the possibility of returning the production condensate to the KA CHPP. The condensate returned from production, if its quality meets production standards, is sent to the deaerator by a pump installed after the collection tank. Otherwise, it is fed to the WLU for appropriate processing (desalination, softening, iron removal, etc.).
CHP is usually equipped with drum spacecraft. From these spacecraft, a small part of the boiler water is discharged with blowing into the continuous blowdown expander and then through the heat exchanger is discharged into the drain. The discharged water is called purge water. The steam obtained in the expander is usually sent to the deaerator.
The principle of operation of the CHP
Let's consider the basic technological scheme of the CHPP (Fig. 4), which characterizes the composition of its parts, the general sequence of technological processes.
Rice. 4. Schematic diagram of the CHP plant.
The structure of the CHPP includes a fuel economy (TF) and devices for its preparation before combustion (PT). The fuel economy includes receiving and unloading devices, transport mechanisms, fuel depots, devices for pre-training fuel (crushing plants).
The products of fuel combustion - flue gases are sucked off by smoke exhausters (DS) and discharged through chimneys (DTR) into the atmosphere. The non-combustible part of solid fuels falls out in the furnace in the form of slag (Sh), and a significant part in the form of small particles is carried away with flue gases. To protect the atmosphere from the release of fly ash, ash collectors (AS) are installed in front of the smoke exhausters. Slags and ash are usually removed to ash dumps. The air necessary for combustion is supplied to the combustion chamber by blow fans. smoke exhausters, chimney, draft fans make up the station draft installation (TDU).
The sections listed above form one of the main technological paths - the fuel-gas-air path.
The second most important technological path of a steam turbine power plant is a steam-water one, including the steam-water part of the steam generator, a heat engine (TD), mainly a steam turbine, a condensing unit, including a condenser (K) and a condensate pump (KN), a technical water supply system (TV) with cooling water pumps ( NOV), water treatment and feed plant, including water treatment (VO), high and low pressure heaters (HPV and HDPE), feed pumps (PN), as well as steam and water pipelines.
In the system of the fuel-gas-air path, the chemically bound energy of the fuel during combustion in the combustion chamber is released in the form of thermal energy transmitted by radiation and convection through the metal walls of the steam generator pipe system to water and the steam formed from water. The thermal energy of the steam is converted in the turbine into the kinetic energy of the flow transferred to the turbine rotor. The mechanical energy of rotation of the turbine rotor connected to the rotor of an electric generator (EG) is converted into energy electric current allocated minus its own consumption to the electrical consumer.
The heat of the working fluid that has worked in the turbines can be used for the needs of external heat consumers (TP).
Heat consumption occurs in the following areas:
1. Consumption for technological purposes;
2. Consumption for heating and ventilation of residential, public and industrial buildings;
3. Consumption for other household needs.
The schedule of technological heat consumption depends on the characteristics of production, mode of operation, etc. Seasonality of consumption in this case occurs only in relatively rare cases. At most industrial enterprises, the difference between winter and summer heat consumption for technological purposes is insignificant. A small difference is obtained only if part of the process steam is used for heating, and also due to an increase in winter time heat loss.
For heat consumers, on the basis of numerous operational data, energy indicators, i.e. consumption rates various types heat production per unit of output.
The second group of consumers, supplied with heat for heating and ventilation purposes, is characterized by a significant uniformity of heat consumption throughout the day and a sharp unevenness of heat consumption throughout the year: from zero in summer to a maximum in winter.
The heat output of heating is directly dependent on the outdoor temperature, i.e. from climatic and meteorological factors.
When heat is released from the plant, steam and hot water heated in network heaters by steam from turbine extractions can serve as heat carriers. The question of choosing one or another coolant and its parameters is decided based on the requirements of the production technology. In some cases, low-pressure steam used in production (for example, after steam hammers) is used for heating and ventilation purposes. Sometimes steam is used to heat industrial buildings in order to avoid installing a separate hot water heating system.
The release of steam to the side for heating purposes is clearly inappropriate, since heating needs can be easily satisfied with hot water, leaving all the heating steam condensate at the station.
The release of hot water for technological purposes is relatively rare. Hot water consumers are only industries that use it for hot washing and other similar processes, and polluted water is no longer returned to the station.
Hot water, released for heating and ventilation purposes, is heated at the station in network heaters with steam from a regulated extraction pressure of 1.17-2.45 bar. At this pressure, water is heated to a temperature of 100-120.
However, when low temperatures outdoor air vacation large quantities heat at such a water temperature becomes impractical, since the amount of water circulating in the network, and, consequently, the consumption of electricity for pumping it increases markedly. Therefore, in addition to the main heaters fed with steam from controlled extraction, peak heaters are installed, to which heating steam with a pressure of 5.85-7.85 bar is supplied from a higher pressure extraction or directly from the boilers through a reduction-cooling unit.
The higher the initial water temperature, the lower the power consumption for the drive of network pumps, as well as the diameter of the heat pipes. At present, in peak heaters, water is most often heated to a temperature of 150 °C from the consumer; with a purely heating load, it usually has a temperature of about 70 °C.
1.4. Heat consumption and efficiency of CHP
Combined heat and power plants release electricity and heat to consumers with steam that has been exhausted in the turbine. In the Soviet Union, it is customary to distribute the costs of heat and fuel between these two types of energy:
2) for the production and release of heat:
 ,
| (3.3) | |
 ,
| (3.3a) |
where 
- heat consumption for external consumer; - heat supply to the consumer; h t is the efficiency of heat supply by a turbine plant, taking into account heat losses during its release (in network heaters, steam pipelines, etc.); h t = 0.98¸0.99.
Total heat consumption for the turbine plant Q tu is made up of the thermal equivalent of the internal power of the turbine 3600 N i, heat consumption for an external consumer Q t and heat loss in the turbine condenser Q j. General Equation heat balance cogeneration turbine plant has the form
For CHP as a whole, taking into account the efficiency of the steam boiler h p.k and efficiency of heat transport h tr we get:
 ;
| (3.6) | |
 .
| (3.6a) |
Value is basically determined by value value - value .
The generation of electricity using waste heat significantly increases the efficiency of electricity generation at CHPPs compared to CPPs and leads to significant fuel savings in the country.
Part one conclusion
Thus, the combined heat and power plant is not a source of large-scale pollution of the location area. Technically and economically justified production planning at CHPPs allows achieving the highest operational performance at the lowest cost of all types of production resources, since at CHPPs the heat of the “spent” steam in the turbines is used for the needs of production, heating and hot water supply
COMPARISON OF RUSSIAN CHPPS WITH FOREIGN
The world's largest electricity producing countries are the United States, China, which produce 20% of world production, and Japan, Russia, and India, which are 4 times inferior to them.
China
China's energy consumption by 2030, according to ExxonMobil's forecast, will more than double. In general, the share of China by this time will account for about 1/3 of the global increase in demand for electricity. This dynamics, according to ExxonMobil, is fundamentally different from the situation in the US, where the demand growth forecast is very moderate.
At present, the structure of China's generating capacities is as follows. About 80% of electricity generated in China is provided by coal-fired thermal power plants, which is associated with the presence of large coal deposits in the country. 15% is provided by hydroelectric power plants, 2% is accounted for by nuclear power plants and 1% each by fuel oil, gas thermal power plants and other power plants (wind, etc.). As for forecasts, in the near future (2020) the role of coal in the Chinese energy sector will remain dominant, but the share of nuclear energy (up to 13%) and the share of natural gas (up to 7%) 1 will significantly increase, the use of which will significantly improve the environmental situation in the rapidly developing cities of China.
Japan
The total installed capacity of power plants in Japan reaches 241.5 million kW. Of these, 60% are thermal power plants (including thermal power plants operating on gas - 25%, fuel oil - 19%, coal - 16%). Nuclear power plants account for 20%, hydroelectric power plants for 19% of the total power generation capacity. In Japan, there are 55 thermal power plants with an installed capacity of over 1 million kW. The largest of them are gas: Kawagoe(Chubu Electric) - 4.8 million kW, higashi(Tohoku Electric) - 4.6 million kW, oil-fired Kashima (Tokyo Electric) - 4.4 million kW and coal-fired Hekinan (Chubu Electric) - 4.1 million kW.
Table 1 - Electricity generation at thermal power plants according to the IEEJ-Institute of Energy Economics, Japan (Institute of Energy Economics, Japan)
India
About 70% of the electricity consumed in India is generated by thermal power plants. The electrification program adopted by the country's authorities has turned India into one of the most attractive markets for investment and promotion of engineering services. For recent years The republic is taking consistent steps to create a full-fledged and reliable electric power industry. The experience of India is notable for the fact that in a country suffering from a shortage of hydrocarbon raw materials, the development of alternative energy sources is being actively pursued. A feature of electricity consumption in India, noted by World Bank economists, is that the growth in household consumption is severely limited by the lack of access to electricity for almost 40% of residents (according to other sources, access to electricity is limited for 43% of urban residents and 55% of rural residents). Another disease of the local power industry is the unreliability of supplies. Power outages are a common situation even in large years and industrial centers of the country.
According to the International Energy Agency, given the current economic realities, India is one of the few countries where a steady increase in electricity consumption is expected in the foreseeable future. The economy of this country, second in the world in terms of population, is one of the fastest growing. Over the past two decades, the average annual GDP growth has been 5.5%. In the 2007/08 financial year, according to the Central Statistical Organization of India, GDP reached $1,059.9 billion, making the country the 12th largest economy in the world. The structure of GDP is dominated by services (55.9%), followed by industry (26.6%) and Agriculture(17.5%). At the same time, according to unofficial data, in July this year, a kind of five-year record was set in the country - demand for electricity exceeded supply by 13.8%.
More than 50% of India's electricity is generated by coal-fired thermal power plants. India is both the world's third largest producer of coal and the world's third largest consumer of this resource, while remaining a net exporter of coal. This type of fuel remains the most important and most economical for India's energy industry, where up to a quarter of the population lives below the poverty line.
Great Britain
Today in the UK, coal-fired power plants produce about a third of the electricity the country needs. Such power plants emit millions of tons of greenhouse gases and particulate toxic particles into the atmosphere, so environmentalists constantly urge the government to immediately close these power plants. But the problem is that there is nothing to replenish that part of the electricity generated by thermal power plants.
Conclusion for part two
Thus, Russia is inferior to the world's largest electricity producing countries, the United States and China, which generate 20% of world production each, and is on a par with Japan and India.
CONCLUSION
This essay describes the types of combined heat and power plants. The schematic diagram, the purpose of the structure elements and the description of their work are considered. The main efficiency of the station has been determined.
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1 - electric generator; 2 - steam turbine; 3 - control panel; 4 - deaerator; 5 and 6 - bunkers; 7 - separator; 8 - cyclone; 9 - boiler; 10 – heating surface (heat exchanger); 11 - chimney; 12 - crushing room; 13 - storage of reserve fuel; 14 - wagon; 15 - unloading device; 16 - conveyor; 17 - smoke exhauster; 18 - channel; 19 - ash catcher; 20 - fan; 21 - firebox; 22 - mill; 23- pumping station; 24 - water source; 25- circulation pump; 26 – high pressure regenerative heater; 27 - feed pump; 28 - capacitor; 29 - installation chemical cleaning water; 30 - step-up transformer; 31 – low pressure regenerative heater; 32 - condensate pump.
The diagram below shows the composition of the main equipment of a thermal power plant and the interconnection of its systems. According to this scheme, it is possible to trace the general sequence of technological processes occurring at TPPs.
Designations on the TPP diagram:
- Fuel economy;
- fuel preparation;
- intermediate superheater;
- part of the high pressure (CHVD or CVP);
- low pressure part (LPH or LPC);
- electric generator;
- auxiliary transformer;
- communication transformer;
- main switchgear;
- condensate pump;
- circulation pump;
- source of water supply (for example, a river);
- (PND);
- water treatment plant (VPU);
- thermal energy consumer;
- reverse condensate pump;
- deaerator;
- feed pump;
- (PVD);
- slag and ash removal;
- ash dump;
- smoke exhauster (DS);
- chimney;
- blower fans (DV);
- ash catcher.
Description of the technological scheme of TPP:
Summarizing all of the above, we obtain the composition of a thermal power plant:
- fuel economy and fuel preparation system;
- boiler plant: a combination of the boiler itself and auxiliary equipment;
- turbine plant: steam turbine and its auxiliary equipment;
- water treatment and condensate treatment plant;
- technical water supply system;
- ash and slag removal system (for thermal power plants operating on solid fuel);
- electrical equipment and electrical equipment control system.
The fuel economy, depending on the type of fuel used at the station, includes a receiving and unloading device, transport mechanisms, fuel depots for solid and liquid fuels, devices for preliminary fuel preparation (crushing plants for coal). The composition of the fuel oil economy also includes pumps for pumping fuel oil, fuel oil heaters, filters.
Training solid fuel for combustion consists of grinding and drying it in a pulverizing plant, and the preparation of fuel oil consists in heating it, cleaning it from mechanical impurities, and sometimes processing it with special additives. Everything is easier with gas fuel. Preparation of gas fuel is reduced mainly to the regulation of gas pressure in front of the boiler burners.
The air necessary for fuel combustion is supplied to the combustion space of the boiler by blow fans (DV). The products of fuel combustion - flue gases - are sucked off by smoke exhausters (DS) and discharged through chimneys into the atmosphere. The set of channels (air ducts and gas ducts) and various elements equipment through which air and flue gases pass, forms a gas-air path of a thermal power plant (heating plant). The smoke exhausters, a chimney and blast fans included in its composition make up a draft installation. In the combustion zone of the fuel, the non-combustible (mineral) impurities included in its composition undergo chemical and physical transformations and are partially removed from the boiler in the form of slag, and a significant part of them is carried out by flue gases in the form of fine ash particles. For guard atmospheric air from ash emissions, ash collectors are installed in front of smoke exhausters (to prevent their ash wear).
Slag and trapped ash are usually removed hydraulically to ash dumps.
When burning fuel oil and gas, ash collectors are not installed.
When fuel is burned, chemically bound energy is converted into heat. As a result, combustion products are formed, which in the heating surfaces of the boiler give off heat to water and the steam formed from it.
The set of equipment, its individual elements, pipelines through which water and steam move, form the steam-water path of the station.
In the boiler, the water is heated to saturation temperature, evaporates, and the saturated steam formed from the boiling boiler water is superheated. From the boiler, superheated steam is sent through pipelines to the turbine, where its thermal energy is converted into mechanical energy transmitted to the turbine shaft. The steam exhausted in the turbine enters the condenser, gives off heat to the cooling water and condenses.
At modern thermal power plants and thermal power plants with units with a unit capacity of 200 MW and more, reheating of the steam is used. In this case, the turbine has two parts: a high pressure part and a low pressure part. The steam exhausted in the high-pressure section of the turbine is sent to an intermediate superheater, where heat is additionally supplied to it. Next, the steam returns to the turbine (to the low pressure part) and from it enters the condenser. Intermediate steam superheating increases the efficiency of the turbine plant and increases the reliability of its operation.
Condensate is pumped out of the condenser by a condensate pump and, after passing through low pressure heaters (LPH), enters the deaerator. Here it is heated by steam to saturation temperature, while oxygen and carbon dioxide are released from it and removed into the atmosphere to prevent equipment corrosion. Deaerated water, called feed water, is pumped through high pressure heaters (HPH) to the boiler.
The condensate in the HDPE and the deaerator, as well as the feed water in the HPH, are heated by steam taken from the turbine. This method of heating means the return (regeneration) of heat to the cycle and is called regenerative heating. Thanks to it, the flow of steam into the condenser is reduced, and, consequently, the amount of heat transferred to the cooling water, which leads to an increase in the efficiency of the steam turbine plant.
The set of elements that provide the condensers with cooling water is called the service water supply system. It includes: a source of water supply (a river, a reservoir, a cooling tower - a cooling tower), a circulation pump, inlet and outlet conduits. In the condenser, about 55% of the heat of the steam entering the turbine is transferred to the cooled water; this part of the heat is not used to generate electricity and is wasted.
These losses are significantly reduced if partially exhausted steam is taken from the turbine and its heat is used for the technological needs of industrial enterprises or for heating water for heating and hot water supply. Thus, the station becomes a combined heat and power plant (CHP), which provides combined generation of electrical and thermal energy. At CHPPs, special turbines with steam extraction are installed - the so-called cogeneration turbines. The condensate of the steam given to the heat consumer is returned to the CHP plant by a return condensate pump.
At TPPs, there are internal losses of steam and condensate due to incomplete tightness of the steam-water path, as well as non-returnable consumption of steam and condensate for the technical needs of the station. They make up approximately 1 - 1.5% of the total steam flow to the turbines.
At CHPPs, there may be external losses of steam and condensate associated with the supply of heat to industrial consumers. On average, they are 35 - 50%. Internal and external losses of steam and condensate are replenished with make-up water pre-treated in the water treatment plant.
Thus, boiler feed water is a mixture of turbine condensate and make-up water.
The electrical facilities of the station include an electric generator, a communication transformer, a main switchgear, a power supply system for the power plant's own mechanisms through an auxiliary transformer.
The control system collects and processes information about the progress technological process and equipment condition, automatic and remote control mechanisms and regulation of the main processes, automatic protection equipment.
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