Class: 9
Goals: to form students' understanding of the Russian electric power industry as the avant-garde branch of the country's national economy.
Tasks:
- educational: deepen students' knowledge of the fuel and energy complex of Russia; explain the concepts of "electric power industry" and "energy system"; give an idea of the role and importance of the electric power industry for the industry and the population of the country;
- Educational: to develop in students the skills and abilities of working with a map and text; promote the development of analytical and logical thinking;
- Educational: to cultivate interest in the geography of the native country, its economy and ecology.
Lesson type: combined.
Technical training aids and material support: Computer included - 1 set, Video projector - 1 pc., Interactive whiteboard - 1 pc., Computer programs and media - 1 set, "Electric power industry of Russia" map, student atlases, presentation ( Attachment 1) photographs of various power plants, diagrams, video.
Terminological apparatus: power plant, thermal power plant, hydroelectric power station, nuclear power plant, alternative energy sources, energy system.
Time: 45 minutes.
During the classes
I. Organizational moment (1 min.)
II. Homework survey (8 min.)
Test. Work with the text of the presentation.
The largest coal reserves (general geological) are concentrated in: (slide 3)
A) Kuznetsk basin
B) Pechora basin
B) Tunguska basin
D) Donets Basin
The first place in Russia in terms of coal reserves is occupied by the basin (slide 4)
A) Kuznetsky
B) Pechorsky
B) South Yakut
The cheapest coal (2-3 times cheaper than Kuznetsk) in the pool (slide 5)
A) Pechorsky
B) Donetsk
B) Kansk-Achinsk
The largest oil and gas base in Russia is (slide 6)
A) Western Siberia
B) the Volga region
B) the Barents Sea
On the territory of Russia there are (slide 7)
A) 26 refineries
B) 22 refineries
C) 30 refineries
D) 40 refineries
The total length of gas pipelines in Russia is (slide 8)
A) 140 thousand km
B) 150 thousand km
C) 170 thousand km
D) 120 thousand km
In terms of gas reserves, Russia ranks in the world (slide 9)
A) 1st place
B) 2nd place
C) 3rd place
Draw a diagram "Composition of the fuel and energy complex"
Working with text (students receive cards with text, identify errors in it and correct them). Answers: 1) B; 2) A; 3) B; 4) A; 5) A; 6) B; 7) A. (slide 10). Peer review of work in pairs. Appendix 2
III. Learning a new topic (slide 12) (30 min.)
Plan.
- Importance of the electric power industry for the country.
- Alternative energy sources.
1. Importance of the electric power industry for the country.
Write the definition in a notebook (slide 13)
Electricity is an industry that produces electricity at power plants and transmits it over a distance through power lines.
Work with the statistical material of the textbook table (p. 125) "Dynamics of electricity production in Russia over the past 20 years." There is a decline in production at the end of the 1990s, an increase in production at the present time.
Energy consumers (slide 14)
The main requirement is the reliability of power supply. To do this, they try to connect all power plants with power lines (TL) so that a sudden failure of one of them can be compensated by others. This is how the Unified Energy System (UES) of the country is formed (slide 15).
The UES of the country in the electric power industry combines the production, transmission and distribution of electricity between consumers. In the power system, each power plant has the opportunity to choose the most economical mode of operation. The UES of Russia unites more than 700 large power plants, in which more than 84% of the capacity of all power plants in the country is concentrated (slide 16). Slide map (slide 17).
The production of electricity at stations of various types is shown in the diagram (slide 18).
Location factors for power plants of different types: (slide 19).
Each of the power plants has its own characteristics. Let's consider them.
Types of power plants:
2. TPP- thermal. They operate on traditional fuels: coal, fuel oil, gas, peat, oil shale.
Efficiency -30-70% (slide 20, 21).
TPP location factors (slide 22).
CHP is a type of thermal power plants (slide 23).
Advantages and disadvantages of thermal power plants (slide 24).
The largest TPP in our country is the Surgut TPP (small message from a student - ahead of schedule) (slide 25).
The next type is
hydroelectric power plants
3. HPP– hydraulic. Use the energy of falling or moving water efficiency - 80% (slide 26).
The location of the hydroelectric power station is determined by the map "Hydropower resources of Russia" (slide 27).
Cascades of hydroelectric power stations have been built on the largest rivers (slide 28).
Advantages and disadvantages of hydroelectric power plants (slide 29).
The largest hydroelectric power plant in Russia is Sayano-Shushenskaya (6.4 MW), where a man-made disaster occurred in 2009 (slide 30).
The Cheboksary HPP is the closest to the Republic of Mari El (slide 31).
Nuclear power plants.
4. NPP- nuclear power plants. They use the energy of nuclear fission.
- Efficiency -30-35% (slide 32).
The principle of operation of the nuclear power plant can be viewed in the video clip (slide 33) ( Appendix 3 , Appendix 4). We see the location of the nuclear power plant on the map (slide 34).
Advantages and disadvantages of nuclear power plants (slide 35).
The considered types of power plants operate on the combustion of mineral fuel, which will inevitably end after a certain period of time. Alternative energy sources will be required to meet future electricity needs.
5. Alternative energy sources
Alternative power plants (slide 36). Consider the types of alternative forms of energy.
- solar energy. A solar battery plant is being built in Chuvashia (slide 37). (38) Solar panels are already in practical use in the capital of the republic. In the Botanical Garden of Yoshkar-Ola, the greenhouse is illuminated and heated with the help of solar energy (slide 39).
- Wind energy. Slide (40) shows wind engines and a windmill of the open-air museum in Kozmodemyansk, Republic of Mari El. Such mills were used in many settlements of the country.
- Internal energy of the Earth. (slide 41). In which region of the country are GTPPs located? (slide 42).
- Tidal energy is used at the Kislogubskaya TPP (slide 43)
IV. Reflection (4 min.)
What new things have you learned for yourself?
- What type of power plants prevails in Russia?
- What is the difference between power plants and stations?
- Where is the best place to build a hydroelectric power plant?
- Where are nuclear power plants built?
- What is an energy system?
V. Homework (2 min).
(slide 44, 45) Read the textbook paragraph 23. Put on the contour map: Balakovo, Beloyarskaya, Bilibinskaya, Bratkaya, Volzhskaya, Zeyskaya, Kola, Konakovskaya, Kursk, Leningrad, Obninskaya, Reftinskaya, Smolenskaya, Surgutskaya, Cheboksaryskaya. Write the problems of the electric power industry and try to find a solution to the problem.
For those who wish:
- watch the series "Energy: how it works"
- myenergy.ru
Student grades.
Thank you for the lesson!
Literature.
- Geography of Russia. Population and economy Grade 9. Textbook V.P. Dronov, V.Ya. Rum.
- Lesson developments in geography “Population and economy of Russia” Grade 9. E.A. Zhizina.
- Atlas and contour maps in geography for grade 9.
- Virtual School of Cyril and Methodius. Geography lessons grade 9.
- Map Power industry of Russia Multimedia disk.
- Presentation for the lesson “Power industry. Types of power plants”.
The technological scheme of a thermal power plant reflects the composition and interconnection of its technological systems, the general sequence of processes occurring in them. On fig. 11 shows a schematic diagram of a solid fuel condensing thermal power plant.
The composition of the thermal power plant includes: a fuel economy and a system for preparing fuel for combustion; boiler plant- a combination of the boiler and auxiliary equipment (consists of the boiler itself, a combustion device, a superheater, a water economizer, an air heater, a frame, brickwork, fittings, auxiliary boiler equipment and pipelines); turbine plant- a set of turbine and auxiliary equipment; water treatment and condensate treatment plants; technical water supply system, ash and slag removal system; electrical engineering; power equipment control system.
The fuel economy includes receiving and unloading devices, transport mechanisms, fuel depots for solid and liquid fuels, and devices for preliminary fuel preparation (coal crushers). The fuel oil facilities also include pumps for pumping fuel oil and heaters.
The preparation of solid fuel for combustion consists in 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 in treating it with special additives. Preparation of gas fuel is reduced mainly to the regulation of gas pressure before it enters the boiler.
The air necessary for fuel combustion is supplied to the boiler by blowers. Products of combustion of fuel - flue gases are sucked off by smoke exhausters and removed through chimneys to the atmosphere. The combination of channels (air ducts and gas ducts) and various elements of equipment through which air and flue gases pass form gas-
air path of a thermal power plant. The smoke exhausters, chimney and blowers included in it are draft installation. In the combustion zone of the fuel, the non-combustible (mineral) impurities included in its composition undergo physical and chemical transformations and are partially removed from the boiler in the form of slag, and a significant part of them are carried away by flue gases in the form of fine ash particles. To protect 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 outside the territory of the power plant to ash dumps. When burning fuel oil and gas, ash collectors are not installed.
When fuel is burned, chemically bound energy is converted into thermal energy, combustion products are formed, which in the heating surfaces of the boiler give off heat to water and the steam formed from it.
The totality of equipment, its individual elements, pipelines through which water and steam move, forms water steam 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. Next, the 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.
From the condenser, the steam converted into water is pumped out by the condensate pump and, after passing through the low pressure heaters (LPH), enters the deaerator. Here, water is heated by steam to saturation temperature, while oxygen and other gases are removed into the atmosphere to prevent corrosion of equipment. From the deaerator, water called nutritional , is pumped through the high-pressure heaters (HPH) by a feed pump and fed into 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 condensers with cooling water is called technical water supply system. It includes a source of water supply (river, reservoir, cooling tower - 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 cooling water; this part of the heat is not used to generate electricity and is wasted uselessly.
These losses will be 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. 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 extractions are installed - the so-called cogeneration turbines. The condensate of the steam given to the heat consumer is supplied to the CHP plant by a return condensate pump.
CHP plants may have external steam and condensate losses associated with the release 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.
TPPs are internal condensate and steam losses, due to incomplete tightness of the water-steam path, as well as the irretrievable consumption of steam and condensate for the technical needs of the station. They make up a small fraction of the total steam flow for turbines (about 1 - 1.5%).
In this way, 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 for power equipment at thermal power plants collects and processes information on the progress of the technological process and the state of equipment, automatic and remote control of mechanisms and regulation of basic processes, automatic protection of equipment.
Security questions for chapter 3
1. What types of power plants do you know?
2. What is the difference between thermal power plants and nuclear?
3. What methods of converting thermal energy into mechanical energy do you know?
4. What is the difference between a boiler plant and a turbine plant?
5. Give the definitions of a draft installation and a water-steam path of the station.
6. What is boiler feed water?
7. What is a technical water supply system?
8. What is the difference between external losses and internal losses of condensate and steam?
WATER PREPARATION
YOUTH AND SPORT OF UKRAINE
YU.BUT. GICHEV
THERMAL POWER PLANTS
Chastb I
Dnepropetrovsk NMetAU 2011
MINISTRY OF EDUCATION AND SCIENCE,
YOUTH AND SPORT OF UKRAINE
NATIONAL METALLURGICAL ACADEMY OF UKRAINE
YU.BUT. GICHEV
THERMAL POWER PLANTS
Chastb I
Ill 23. Bibliography: 4 names.
Responsible for the release, Dr. tech. sciences, prof.
Reviewers: , Dr. tech. sciences, prof. (DNURT)
Cand. tech. Sciences, Assoc. (NMetAU)
© National Metallurgical
Academy of Ukraine, 2011
INTRODUCTION…………………………………………………………………………..4
1 GENERAL INFORMATION ABOUT THERMAL POWER PLANTS………………...5
1.1 Definition and classification of power plants………………………….5
1.2 Technological scheme of thermal power plant………………………8
1.3 Technical and economic indicators of TPP……………………………….11
1.3.1 Energy indicators…………………………………….11
1.3.2 Economic indicators…………………………………….13
1.3.3 Performance indicators………………………………...15
1.4 Requirements for TPP………………………………………16
1.5 Features of industrial thermal power plants………………16
2 CONSTRUCTION OF THERMAL SCHEMES OF TPP………………………………………...17
2.1 General concepts of thermal circuits……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….
2.2 Initial steam parameters……………………………………………….18
2.2.1 Initial steam pressure……………………………………….18
2.2.2 Initial steam temperature…………………………………...20
2.3 Reheating steam…………………………………………..22
2.3.1 Energy efficiency of reheat...24
2.3.2 Reheat pressure…………………………26
2.3.3 Technical implementation of reheating……27
2.4 Final steam parameters………………………….…………………….29
2.5 Regenerative heating of feed water…………………………...30
2.5.1 Energy efficiency of regenerative heating..30
2.5.2 Technical implementation of regenerative heating…....34
2.5.3 Regenerative feed water heating temperature..37
2.6 Construction of thermal schemes of thermal power plants based on the main types of turbines……..39
2.6.1 Construction of a thermal scheme based on the turbine "K"…………...39
2.6.2 Construction of a thermal scheme based on the turbine "T"….………..41
LITERATURE……………………………………………………………………...44
INTRODUCTION
The discipline "Thermal Power Plants" for a number of reasons is of particular importance among the disciplines read for the specialty 8 (7). - thermal power engineering.
Firstly, from a theoretical point of view, the discipline accumulates the knowledge gained by students in almost all the main previous disciplines: "Fuel and its combustion", "Boiler plants", "Superchargers and heat engines", "Sources of heat supply for industrial enterprises" , "Gas Purification" and others.
Secondly, from a practical point of view, thermal power plants (TPPs) are an integrated energy enterprise that includes all the main elements of the energy economy: a fuel preparation system, a boiler shop, a turbine shop, a system for converting and supplying thermal energy to external consumers, systems for utilizing and neutralizing harmful emissions.
Thirdly, from an industrial point of view, thermal power plants are the dominant power generating enterprises in the domestic and foreign energy sectors. Thermal power plants account for about 70% of electricity generating installed capacity in Ukraine, and taking into account nuclear power plants, where steam turbine technologies are also implemented, the installed capacity is about 90%.
This lecture notes have been developed in accordance with the work program and curriculum for specialty 8(7). - thermal power engineering and as the main topics includes: general information about thermal power plants, principles for constructing thermal circuits of power plants, equipment selection and calculations of thermal circuits, equipment layout and operation of thermal power plants.
The discipline "Thermal Power Plants" contributes to the systematization of the knowledge gained by students, the expansion of their professional horizons and can be used in coursework in a number of other disciplines, as well as in the preparation of diploma works of specialists and master's theses.
1 GENERAL INFORMATION ABOUT THERMAL POWER PLANTS
1.1 Definition and classification of power plants
Power station- an energy enterprise designed to convert various types of fuel and energy resources into electricity.
The main options for the classification of power plants:
I. Depending on the type of converted fuel and energy resources:
1) thermal power plants (TPPs), in which electricity is obtained by converting hydrocarbon fuels (coal, natural gas, fuel oil, combustible VER and others);
2) nuclear power plants (NPPs), in which electricity is obtained by converting atomic energy into nuclear fuel;
3) hydroelectric power plants (HPPs), in which electricity is obtained by converting the mechanical energy of the flow of a natural water source, primarily rivers.
This classification option can also include power plants using non-traditional and renewable energy sources:
solar power plants;
geothermal power plants;
wind power plants;
· tidal power plants and others.
II. For this discipline, a more in-depth classification of thermal power plants is of interest, which, depending on the type of heat engines, are divided into:
1) steam turbine power plants (STP);
2) gas turbine power plants (GTP);
3) combined cycle power plants (CGE);
4) power plants on internal combustion engines (ICE).
Among these power plants, steam turbine power plants are dominant, accounting for more than 95% of the total installed capacity of thermal power plants.
III. Depending on the type of energy carriers supplied to an external consumer, steam turbine power plants are divided into:
1) condensing power plants (CPPs), which supply only electricity to an external consumer;
2) combined heat and power plants (CHP) that supply external consumers with both thermal and electrical energy.
IV. Depending on the purpose and departmental subordination, power plants are divided into:
1) regional power plants, which are designed to provide electricity to all consumers in the region;
2) industrial power plants, which are part of industrial enterprises and are designed to provide electricity primarily to consumers of enterprises.
V. Depending on the duration of use of the installed capacity during the year, power plants are divided into:
1) basic (B): 6000 ÷ 7500 h / year, i.e. over 70% of the duration of the year;
2) semi-basic (P/B): 4000÷6000 h/year, 50÷70%;
3) semi-peak (P/P): 2000÷4000 h/year, 20÷50%;
4) peak (P): up to 2000 h/year, up to 20% of the duration of the year.
This classification option can be illustrated by the example of a graph of the duration of electrical loads:
Figure 1.1 - Graph of the duration of electrical loads
VI. Depending on the pressure of the steam entering the turbines, steam turbine thermal power plants are divided into:
1) low pressure: up to 4 MPa;
2) medium pressure: up to 9 - 13 MPa;
3) high pressure: up to 25 - 30 MPa, including:
● subcritical pressure: up to 18 - 20 MPa
● critical and supercritical pressure: over 22 MPa
VII. Depending on the power, steam turbine power plants are divided into:
1) low-capacity power plants: total installed capacity up to 100 MW with a unit capacity of installed turbine generators up to 25 MW;
2) medium power: total installed power up to 1000 MW with a unit power of installed turbogenerators up to 200 MW;
3) high power: the total installed power is over 1000 MW with a unit power of installed turbogenerators over 200 MW.
VIII. Depending on the method of connecting steam generators to turbogenerators, thermal power plants are divided into:
1) centralized (non-block) TPPs, in which steam from all boilers enters one central steam pipeline, and then is distributed among turbogenerators (see Fig. 1.2);
1 – steam generator; 2 - steam turbine; 3 - central (main) steam pipeline; 4 – steam turbine condenser; 5 - electric generator; 6 - transformer.
Figure 1.2 - Schematic diagram of a centralized (non-block) TPP
2) block thermal power plants, in which each of the installed steam generators is connected to a well-defined turbogenerator (see Fig. 1.3).
1 – steam generator; 2 - steam turbine; 3 – intermediate superheater; 4 – steam turbine condenser; 5 - electric generator; 6 - transformer.
Figure 1.3 - Schematic diagram of a block TPP
Unlike a non-block block diagram of a TPP, it requires less capital costs, is easier to operate and creates conditions for the complete automation of a steam turbine plant of a power plant. In the block diagram, the number of pipelines and production volumes of the station for equipment placement is reduced. When using intermediate superheating of steam, the use of block diagrams is mandatory, because otherwise it is not possible to control the flow of steam released from the turbine for superheating.
1.2 Technological scheme of thermal power plant
The technological scheme depicts the main parts of the power plant, their relationship and, accordingly, shows the sequence of technological operations from the moment fuel is delivered to the station to the supply of electricity to the consumer.
As an example, Figure 1.4 shows a process flow diagram for a pulverized-coal steam turbine power plant. This type of TPP prevails among operating basic thermal power plants in Ukraine and abroad.
Sun - fuel consumption at the station; Dp. d. is the performance of the steam generator; Ds. n. – conditional steam consumption for the station’s own needs; Dt - steam flow to the turbine; Evyr - the amount of generated electricity; Esn - electricity consumption for the station's own needs; Eop - the amount of electricity supplied to an external consumer.
Figure 1.4 - An example of a technological scheme of a steam turbine pulverized coal power plant
It is customary to divide the technological scheme of TPP into three parts, which are marked with dotted lines in Figure 1.4:
I … Fuel-gas-air path, which includes:
1 – fuel economy (unloading device, raw coal storage, crushing plants, crushed coal bunkers, cranes, conveyors);
2 – pulverization system (coal mills, fine fans, coal dust bunkers, feeders);
3 – blower fan for supplying air for fuel combustion;
4 – steam generator;
5 – gas cleaning;
6 - smoke exhauster;
7 - chimney;
8 – baguer pump for transportation of hydroash and slag mixture;
9 – supply of hydroash and slag mixture for disposal.
In general, the fuel-gas-air path includes : fuel economy, dust preparation system, draught-blower means, boiler flues and ash and slag removal system.
II … Steam path, which includes:
10 – steam turbine;
11 – steam turbine condenser;
12 - circulation pump of the circulating water supply system for cooling the condenser;
13 – cooling device of the reverse system;
14 - supply of additional water, compensating for water losses in the circulating system;
15 – supply of raw water for the preparation of chemically purified water, which compensates for the loss of condensate at the station;
16 - chemical water treatment;
17 – chemical water treatment pump supplying additional chemically treated water to the exhaust steam condensate stream;
18 – condensate pump;
19 – regenerative low-pressure feed water heater;
20 - deaerator;
21 - feed pump;
22 – regenerative high-pressure feed water heater;
23 – drainage pumps for removal of heating steam condensate from the heat exchanger;
24 – regenerative steam extractions;
25 - Intermediate superheater.
In general, the steam-water path includes: steam-water part of the boiler, turbine, condensate unit, systems for the preparation of cooling circulating water and additional chemically treated water, a system for regenerative heating of feed water and deaeration of feed water.
III … Electrical part, which includes:
26 – electric generator;
27 - step-up transformer for electricity supplied to an external consumer;
28 - busbars of the open switchgear of the power plant;
29 – transformer for electric power of own needs of the power plant;
30 - busbars of the distributing device of the electric power of own needs.
Thus, the electrical part includes: power generator, transformers and distribution busbars.
1.3 Technical and economic indicators of TPP
The technical and economic indicators of TPPs are divided into 3 groups: energy, economic and operational, which, respectively, are designed to assess the technical level, efficiency and quality of operation of the plant.
1.3.1 Energy performance
The main energy indicators of TPPs include: k.p.d. power plants (), specific heat consumption (), specific fuel consumption for electricity generation ().
These indicators are called indicators of thermal efficiency of the station.
According to the results of the actual operation of the power plant, efficiency is determined by the relations:
; (1.1)
; (1.2)
When designing a power plant and for analyzing its operation, efficiency are determined by products that take into account the efficiency. individual elements of the station:
where ηkot, ηturbo – efficiency boiler and turbine shops;
ηt. p. - k.p.d. heat flow, which takes into account heat losses by heat carriers inside the station due to heat transfer to the environment through the pipeline walls and heat carrier leaks, ηt. n. = 0.98 ... 0.99 (cf. 0.985);
esn is the share of electricity spent for the power plant's own needs (electric drive in the fuel preparation system, drive of the draft equipment of the boiler shop, pump drive, etc.), esn = Esn/Evyr = 0.05…0.10 (cf. 0.075);
qsn is the share of heat consumption for own needs (chemical water treatment, deaeration of feed water, operation of steam ejectors providing vacuum in the condenser, etc.), qsn = 0.01…0.02 (cf. 0.015).
K. p.d. the boiler shop can be represented as a k.p.d. steam generator: ηcat = ηp. d. = 0.88…0.96 (cf. 0.92)
K. p.d. turbine shop can be represented as an absolute electrical efficiency. turbogenerator:
ηturb = ηt. g. = ηt ηoi ηm, (1.5)
where ηt is the thermal efficiency. cycle of a steam turbine plant (ratio of used heat to supplied heat), ηt = 0.42…0.46 (cf. 0.44);
ηoi is the internal relative efficiency. turbines (taking into account losses inside the turbine due to steam friction, overflows, ventilation), ηoi = 0.76…0.92 (cf. 0.84);
ηm - electromechanical efficiency, which takes into account the losses in the transfer of mechanical energy from the turbine to the generator and the losses in the electric generator itself, ηeng = 0.98 ... 0.99 (cf. 0.985).
Taking into account the product (1.5), expression (1.4) for the efficiency net power plant takes the form:
ηsnet = ηpg ηt ηoi ηm ηtp (1 – esn) (1 – qsn); (1.6)
and after substituting the average values will be:
ηsnet = 0.92 0.44 0.84 0.985 0.985 (1 - 0.075) (1 - 0.015) = 0.3;
In general, for a power plant, the efficiency net changes within: ηsnet = 0.28…0.38.
The specific heat consumption for electricity generation is determined by the ratio:
, (1.7)
where Qfuel is the heat received from fuel combustion 
.
; (1.8)
where rn is the normative coefficient of efficiency of capital investments, year-1.
The reciprocal value of pH gives the payback period, for example, at pH = 0.12 year-1, the payback period will be:
These costs are used to select the most economical option for building a new or reconstructing an existing power plant.
1.3.3 Performance
Performance indicators evaluate the quality of operation of the power plant and in particular include:
1) staffing factor (number of service personnel per 1 MW of installed capacity of the plant), W (persons/MW);
2) the utilization factor of the installed capacity of the power plant (the ratio of the actual electricity generation to the maximum possible generation)
; (1.16)
3) the number of hours of use of installed capacity
4) equipment availability factor and equipment technical utilization factor
; (1.18)
Equipment readiness factors for the boiler and turbine shops are: Kgotkot = 0.96…0.97, Kgotturb = 0.97…0.98.
The coefficient of utilization of equipment for thermal power plants is: KispTES = 0.85 ... 0.90.
1.4 Requirements for TPP
The requirements for TPPs are divided into 2 groups: technical and economic.
The technical requirements include:
Reliability (uninterrupted power supply in accordance with the requirements of consumers and the dispatch schedule of electrical loads);
Maneuverability (the ability to quickly increase or remove the load, as well as start or stop the units);
· thermal efficiency (maximum efficiency and minimum specific fuel consumption for various operating modes of the station);
· environmental friendliness (minimum harmful emissions into the environment and not exceeding the permissible emissions under various operating modes of the station).
Economic Requirements are reduced to the minimum cost of electricity, subject to compliance with all technical requirements.
1.5 Features of industrial thermal power plants
Among the main features of industrial thermal power plants are:
1) two-way communication of the power plant with the main technological shops (the power plant provides the electrical load of the technological shops and, in accordance with the need, changes the supply of electricity, and the shops in some cases are sources of thermal and combustible RES that are used at power plants);
2) the commonality of a number of systems of power plants and technological shops of the enterprise (fuel supply, water supply, transport facilities, repair base, which reduces the cost of building a station);
3) the presence at industrial power plants, in addition to turbogenerators, of turbocompressors and turboblowers for supplying process gases to the enterprise's workshops;
4) the predominance of thermal power plants (CHP) among industrial power plants;
5) relatively small capacity of industrial thermal power plants:
70…80%, ≤ 100 MW.
Industrial thermal power plants provide 15 ... 20% of the total electricity generation.
2 CONSTRUCTION OF THERMAL SCHEMES OF TPP
2.1 General concepts of thermal schemes
Thermal schemes refer to steam-water paths of power plants and show :
1) the relative position of the main and auxiliary equipment of the station;
2) technological connection of the equipment through the lines of the pipeline of heat carriers.
Thermal schemes can be divided into 2 types:
1) fundamental;
2) deployed.
In the schematic diagrams, the equipment is shown to the extent necessary for calculating the thermal circuit and analyzing the calculation results.
Based on the schematic diagram, the following tasks are solved:
1) determine the flow rates and parameters of heat carriers in various elements of the circuit;
2) choose equipment;
3) develop detailed thermal schemes.
Expanded thermal schemes include all station equipment, including backup, all station pipelines with shut-off and control valves.
Based on the detailed schemes, the following tasks are solved:
1) mutual placement of equipment in the design of power plants;
2) execution of working drawings during design;
3) operation of stations.
The construction of thermal schemes is preceded by the solution of the following questions:
1) the choice of the type of plant, which is carried out on the basis of the type and number of expected energy loads, i.e. IES or CHP;
2) determine the electrical and thermal power of the station as a whole and the power of its individual blocks (aggregates);
3) choose the initial and final parameters of the steam;
4) determine the need for intermediate overheating of the steam;
5) choose the types of steam generators and turbines;
6) develop a scheme for regenerative heating of feed water;
7) combine the main technical solutions according to the thermal scheme (capacity of the units, steam parameters, type of turbines) with a number of auxiliary issues: preparation of additional chemically treated water, water deaeration, utilization of steam generator blowdown water, drive of feed pumps and others.
The development of thermal schemes is mainly influenced by 3 factors:
1) the value of the initial and final steam parameters in the steam turbine plant;
2) intermediate superheating of steam;
3) regenerative heating of feed water.
2.2 Initial steam parameters
The initial steam parameters are the pressure (P1) and temperature (t1) of the steam upstream of the turbine stop valve.
2.2.1 Initial steam pressure
The initial steam pressure affects the efficiency. power plants and, first of all, through thermal efficiency. cycle of a steam turbine plant, which, when determining the efficiency. power plant has a minimum value (ηt = 0.42…0.46):
To determine the thermal efficiency. can be used iS- water vapor diagram (see Fig. 2.1):
(2.2)
where Nad is the adiabatic heat loss of steam (for an ideal cycle);
qsubv - the amount of heat supplied to the cycle;
i1, i2 – steam enthalpy before and after the turbine;
i2" is the enthalpy of the condensate of the steam exhausted in the turbine (i2" = cpt2).
Figure 2.1 - To the definition of thermal efficiency.
The results of calculation by formula (2.2) give the following efficiency values:
ηt, fractions of units
Here, 3.4 ... 23.5 MPa are the standard steam pressures adopted for steam turbine power plants in the energy sector of Ukraine.
It follows from the calculation results that with an increase in the initial steam pressure, the efficiency value increases. Together with that, pressure increase has a number of negative consequences:
1) with an increase in pressure, the volume of steam decreases, the flow area of the turbine flow path and the length of the blades decrease, and, consequently, steam flows increase, which leads to a decrease in the internal relative efficiency. turbines (ηоі);
2) an increase in pressure leads to an increase in steam losses through the turbine end seals;
3) the consumption of metal for equipment and the cost of the steam turbine plant increase.
To eliminate the negative impact along with an increase in pressure, the power of the turbine should be increased, which ensures :
1) increase in steam consumption (excludes a decrease in the flow area in the turbine and the length of the blades);
2) reduces the relative knocking out of steam through the mechanical seals;
3) an increase in pressure together with an increase in power makes it possible to make pipelines more compact and reduce metal consumption.
The optimal ratio between the initial steam pressure and turbine power, obtained on the basis of an analysis of the operation of operating power plants abroad, is shown in Figure 2.2 (the optimal ratio is marked with hatching).
Figure 2.2 - Relationship between turbogenerator power (N) and initial steam pressure (P1).
2.2.2 Initial steam temperature
With an increase in the initial steam pressure, the moisture content of the steam at the outlet of the turbine increases, which is illustrated by graphs on the iS - diagram (see Fig. 2.3).
P1 > P1" > P1"" (t1 = const, P2 = const)
x2< x2" < x2"" (y = 1 – x)
y2 > y2" > y2""
Figure 2.3 - The nature of the change in the final moisture content of the steam with an increase in the initial steam pressure.
The presence of steam moisture increases friction losses, reduces the internal relative efficiency. and causes drip erosion of the blades and other elements of the flow path of the turbine, which leads to their destruction.
The maximum permissible steam humidity (y2dop) depends on the length of the blades (ll); for example:
ll ≤ 750…1000 mm y2perm ≤ 8…10%
ll ≤ 600 mm y2adm ≤ 13%
To reduce the humidity of the steam, along with an increase in the steam pressure, its temperature should be increased, which is illustrated in Figure 2.4.
t1 > t1" > t1"" (P2 = const)
x2 > x2" > x2"" (y = 1 - x)
y2< y2" < y2""
Figure 2.4 - The nature of the change in the final moisture content of the steam with an increase in the initial temperature of the steam.
The steam temperature is limited by the heat resistance of the steel from which the superheater, pipelines, and turbine elements are made.
It is possible to use steels of 4 classes:
1) carbon and manganese steels (with limiting temperature tpr ≤ 450…500°С);
2) chromium-molybdenum and chromium-molybdenum-vanadium steels of pearlite class (tpr ≤ 570…585°С);
3) high-chromium steels of martensite-ferritic class (tpr ≤ 600…630°С);
4) stainless chromium-nickel steels of the austenitic class (tpr ≤ 650…700°С).
When moving from one class of steel to another, the cost of equipment increases dramatically.
Steel class
Relative cost
At this stage, from an economic point of view, it is expedient to use pearlitic steel with a working temperature tr ≤ 540°C (565°C). Martensite-ferritic and austenitic steels lead to a sharp increase in the cost of equipment.
The influence of the initial steam temperature on the thermal efficiency should also be noted. steam turbine cycle. An increase in steam temperature leads to an increase in thermal efficiency:
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 of chemical water treatment; 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, and 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.
The preparation of 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 treating 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 combination of channels (air ducts and gas ducts) and various elements of equipment through which air and flue gases pass forms the 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 fuel combustion zone, 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. To protect 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 its 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 the TPP, 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 on the course of the technological process and the state of the equipment, automatic and remote control of mechanisms and regulation of the main processes, automatic protection of equipment.
Most often in modern energy, traditional and non-traditional energy are distinguished.
The traditional energy sector is mainly divided into electric power industry and thermal power industry.
The most convenient type of energy is electrical, which can be considered the basis of civilization. The transformation of primary energy into electrical energy is carried out at power plants.
Our country produces and consumes a huge amount of electricity. It is produced almost entirely by the three main types of power plants: thermal, nuclear and hydroelectric power plants.
Approximately 70% of the world's electricity is generated by thermal power plants. They are divided into condensing thermal power plants (CPP), which produce only electricity, and combined heat and power plants (CHP), which produce electricity and heat.
In Russia, about 75% of energy is produced at thermal power plants. TPPs are built in fuel extraction areas or in energy consumption areas. It is advantageous to build hydroelectric power stations on full-flowing mountain rivers. Therefore, the largest hydroelectric power plants are built on Siberian rivers. Yenisei, Angara. But cascades of hydroelectric power stations have also been built on the flat rivers: the Volga, the Kama.
Nuclear power plants are built in areas where a lot of energy is consumed, and other energy resources are not enough (in the western part of the country).
The main type of power plants in Russia are thermal (TPP). These installations generate approximately 67% of Russia's electricity. Their placement is influenced by fuel and consumer factors. The most powerful power plants are located in the places where fuel is extracted. Thermal power plants using high-calorie, transportable fuel are consumer-oriented.
Fig.1. Schematic diagram of a thermal power plant
Schematic diagram of a thermal power plant is shown in Fig.1. It should be borne in mind that several circuits can be provided in its design - the coolant from the fuel reactor may not immediately go to the turbine, but give up its heat in the heat exchanger to the coolant of the next circuit, which can already enter the turbine, or can further transfer its energy to the next contour. Also, in any power plant, a cooling system for the spent coolant is provided in order to bring the temperature of the coolant to the value required for the recycle. If there is a settlement near the power plant, then this is achieved by using the heat of the waste heat carrier to heat water for heating houses or hot water, and if not, then the excess heat of the waste heat carrier is simply discharged into the atmosphere in cooling towers. Cooling towers are most often used as a condenser for exhaust steam at non-nuclear power plants.
The main equipment of the TPP is a boiler-steam generator, a turbine, a generator, a steam condenser, a circulation pump.
In the steam generator boiler, when fuel is burned, thermal energy is released, which is converted into water vapor energy. In the turbine, the energy of water vapor is converted into mechanical energy of rotation. The generator converts the mechanical energy of rotation into electrical energy. The CHP scheme is different in that, in addition to electrical energy, it also generates heat by removing part of the steam and heating the water supplied to the heat mains with it.
There are thermal power plants with gas turbines. The working fluid and them - gas with air. The gas is released during the combustion of organic fuel and is mixed with heated air. The gas-air mixture at 750-770°C is fed into the turbine, which rotates the generator. Thermal power plants with gas turbines are more maneuverable, easy to start, stop, and regulate. But their power is 5-8 times less than steam ones.
The process of generating electricity at thermal power plants can be divided into three cycles: chemical - the combustion process, as a result of which heat is transferred to steam; mechanical - the thermal energy of steam is converted into rotational energy; electrical - mechanical energy is converted into electrical energy.
The overall efficiency of a TPP consists of the product of the efficiency (η) of the cycles:
The efficiency of an ideal mechanical cycle is determined by the so-called Carnot cycle:
where T 1 and T 2 - steam temperature at the inlet and outlet of the steam turbine.
At modern thermal power plants T 1 =550°C (823°K), T 2 =23°C (296°K).
Practically taking into account losses η TES = 36-39%. Due to the more complete use of thermal energy, the CHP efficiency = 60-65%.
A nuclear power plant differs from a thermal power plant in that the boiler is replaced by a nuclear reactor. The heat of the nuclear reaction is used to produce steam.
The primary energy at nuclear power plants is the internal nuclear energy, which is released during nuclear fission in the form of colossal kinetic energy, which, in turn, is converted into heat. The installation where these transformations take place is called a reactor.
A coolant passes through the reactor core, which serves to remove heat (water, inert gases, etc.). The coolant carries heat into the steam generator, giving it to the water. The resulting water vapor enters the turbine. The reactor power is controlled using special rods. They are introduced into the core and change the neutron flux, and hence the intensity of the nuclear reaction.
The natural nuclear fuel of a nuclear power plant is uranium. For biological protection against radiation, a layer of concrete several meters thick is used.
When burning 1 kg of coal, 8 kWh of electricity can be obtained, and with the consumption of 1 kg of nuclear fuel, 23 million kWh of electricity is generated.
For more than 2000 years, mankind has been using the water energy of the Earth. Now water energy is used in hydropower plants (HPP) of three types:
- hydraulic power plants (HPP);
- tidal power plants (TPP) using the energy of the tides of the seas and oceans;
- pumped-storage stations (PSPPs) that accumulate and use the energy of reservoirs and lakes.
Hydropower resources in the power plant turbine are converted into mechanical energy, which is converted into electrical energy in the generator.
Thus, the main sources of energy are solid fuel, oil, gas, water, the energy of the decay of uranium nuclei and other radioactive substances.
