How is a gas turbine different from a steam turbine? The device and principle of operation of a gas turbine. Head-to-Head Comparison of Reciprocating and Gas Turbine Engines
Thermal turbine of constant action, in which the thermal energy of compressed and heated gas (usually fuel combustion products) is converted into mechanical rotational work on a shaft; is a structural element of a gas turbine engine.
Heating of compressed gas, as a rule, occurs in the combustion chamber. It is also possible to carry out heating in a nuclear reactor, etc. Gas turbines first appeared at the end of the 19th century. as a gas turbine engine and in terms of design, they approached a steam turbine. Structurally, a gas turbine is a series of orderly arranged stationary blade rims of the nozzle apparatus and rotating rims of the impeller, which as a result form a flow part. The turbine stage is a nozzle apparatus combined with an impeller. The stage consists of a stator, which includes stationary parts (housing, nozzle blades, shroud rings), and a rotor, which is a set of rotating parts (such as rotor blades, disks, shaft).
Classification gas turbine It is carried out according to many design features: in the direction of the gas flow, the number of stages, the method of using the heat difference and the method of supplying gas to the impeller. In the direction of the gas flow, gas turbines can be distinguished axial (the most common) and radial, as well as diagonal and tangential. In axial gas turbines, the flow in the meridional section is transported mainly along the entire axis of the turbine; in radial turbines, on the contrary, it is perpendicular to the axis. Radial turbines are divided into centripetal and centrifugal. In a diagonal turbine, the gas flows at some angle to the axis of rotation of the turbine. The impeller of a tangential turbine has no blades; such turbines are used at very low gas flow rates, usually in measuring instruments. Gas turbines are single, double and multi-stage.
The number of stages is determined by many factors: the purpose of the turbine, its design scheme, the total power and developed by one stage, as well as the actuated pressure drop. According to the method of using the available heat difference, turbines with speed stages are distinguished, in which only the flow turns in the impeller, without pressure change (active turbines), and turbines with pressure stages, in which the pressure decreases both in the nozzle apparatus and on the rotor blades (jet turbines). In partial gas turbines, gas is supplied to the impeller along a part of the circumference of the nozzle apparatus or along its full circumference.
In a multistage turbine, the energy conversion process consists of a number of successive processes in individual stages. Compressed and heated gas is supplied to the interblade channels of the nozzle apparatus at an initial speed, where, in the process of expansion, a part of the available heat drop is converted into kinetic energy flow jets. Further expansion of the gas and the conversion of the heat drop into useful work occur in the interblade channels of the impeller. The gas flow, acting on the rotor blades, creates a torque on the main shaft of the turbine. In this case, the absolute velocity of the gas decreases. The lower this speed, the greater part of the gas energy is converted into mechanical work on the turbine shaft.
Efficiency characterizes the efficiency of gas turbines, which is the ratio of the work removed from the shaft to the available gas energy in front of the turbine. The effective efficiency of modern multistage turbines is quite high and reaches 92-94%.
The principle of operation of a gas turbine is as follows: gas is injected into the combustion chamber by a compressor, mixed with air, forms a fuel mixture and is ignited. The resulting combustion products with high temperature (900-1200 °C) pass through several rows of blades mounted on the turbine shaft and cause the turbine to rotate. The resulting mechanical energy of the shaft is transmitted through a gearbox to a generator that generates electricity.
Thermal energy gases leaving the turbine enter the heat exchanger. Also, instead of generating electricity, the mechanical energy of the turbine can be used to operate various pumps, compressors, etc. The most commonly used fuel for gas turbines is natural gas, although this cannot exclude the possibility of using other types of gaseous fuels. But at the same time, gas turbines are very capricious and place high demands on the quality of its preparation (certain mechanical inclusions, humidity are necessary).
The temperature of gases leaving the turbine is 450-550 °С. The quantitative ratio of thermal energy to electrical energy in gas turbines ranges from 1.5: 1 to 2.5: 1, which makes it possible to build cogeneration systems that differ in the type of coolant:
1) direct (direct) use of exhaust hot gases;
2) production of low or medium pressure steam (8-18 kg/cm2) in an external boiler;
3) production of hot water (better when the required temperature exceeds 140 °C);
4) production of high pressure steam.
A great contribution to the development of gas turbines was made by Soviet scientists B. S. Stechkin, G. S. Zhiritsky, N. R. Briling, V. V. Uvarov, K. V. Kholshchevikov, I. I. Kirillov and others. the creation of gas turbines for stationary and mobile gas turbine plants was achieved by foreign companies (the Swiss Brown-Boveri, in which the famous Slovak scientist A. Stodola worked, and Sulzer, the American General Electric, etc.).
IN further development gas turbines depends on the possibility of increasing the gas temperature in front of the turbine. This is due to the creation of new heat-resistant materials and reliable cooling systems for rotor blades with a significant improvement in the flow path, etc.
Thanks to the widespread transition in the 1990s. natural gas as the main fuel for power generation, gas turbines have occupied a significant segment of the market. Despite the fact that the maximum efficiency of the equipment is achieved at capacities from 5 MW and higher (up to 300 MW), some manufacturers produce models in the 1-5 MW range.
Gas turbines are used in aviation and power plants.
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"Turbo", "turbojet", "turboprop" - these terms have become firmly established in the lexicon of 20th century engineers involved in design and maintenance. Vehicle and stationary electrical installations. They are used even in related areas and advertising, when they want to give the name of the product some hint of special power and efficiency. In aviation, rockets, ships and power plants, the gas turbine is most often used. How is it organized? Does it run on natural gas (as the name might suggest), and what are they like? How is a turbine different from other types of internal combustion engine? What are its advantages and disadvantages? An attempt to answer these questions as fully as possible is made in this article.
Russian machine-building leader UEC
Russia, unlike many other independent states formed after the collapse of the USSR, managed to largely preserve the machine-building industry. In particular, the Saturn company is engaged in the production of special-purpose power plants. The gas turbines of this company are used in shipbuilding, the raw materials industry and energy. The products are high-tech, they require a special approach during installation, debugging and operation, as well as special knowledge and expensive equipment during scheduled maintenance. All these services are available to customers of UEC - Gas Turbines, as it is called today. There are not so many such enterprises in the world, although the principle of arranging the main product is at first glance simple. The accumulated experience is of great importance, which makes it possible to take into account many technological subtleties, without which it is impossible to achieve a durable and reliable operation of the unit. Here is just a part of the UEC product range: gas turbines, power plants, gas pumping units. Among the customers are "Rosatom", "Gazprom" and other "whales" of the chemical industry and energy.
The manufacture of such complex machines requires an individual approach in each case. The calculation of a gas turbine is currently fully automated, but the materials and features of the wiring diagrams matter in each individual case.
And it all started so easy...
Searches and couples
The first experiments of converting the translational energy of the flow into rotational force were carried out by mankind in ancient times, using an ordinary water wheel. Everything is extremely simple, liquid flows from top to bottom, blades are placed in its flow. The wheel, equipped with them around the perimeter, is spinning. The windmill works the same way. Then came the age of steam, and the wheel turned faster. By the way, the so-called "eolipil", invented by the ancient Greek Heron about 130 years before the birth of Christ, was a steam engine that works exactly on this principle. In essence, this was the first gas turbine known to historical science (after all, steam is a gaseous state of aggregation of water). Today, however, it is customary to separate these two concepts. Heron's invention was then treated in Alexandria without much enthusiasm, although with curiosity. Turbine-type industrial equipment appeared only at the end of the 19th century, after the creation of the world's first active power unit equipped with a nozzle by the Swede Gustaf Laval. Approximately in the same direction, engineer Parsons worked, supplying his machine with several functionally connected steps.
The birth of gas turbines
A century earlier, a certain John Barber had a brilliant idea. Why do you need to heat the steam first, is it not easier to use directly the exhaust gas generated during the combustion of fuel, and thereby eliminate unnecessary mediation in the energy conversion process? This is how the first real gas turbine came about. The 1791 patent lays out the basic idea of being used in a horseless carriage, but elements of it are used today in modern rocket, aircraft, tank, and automobile engines. The beginning of the process of jet engine building was given in 1930 by Frank Whittle. He came up with the idea of using a turbine to propel an airplane. Later, she found development in numerous turboprop and turbojet projects.
Nikola Tesla gas turbine
The famous scientist-inventor has always approached the issues under study in a non-standard way. It seemed obvious to everyone that wheels with paddles or blades "catch" the movement of the medium better than flat objects. Tesla, in his usual manner, proved that if you assemble a rotor system from discs arranged in series on the axis, then by picking up the boundary layers with a gas flow, it will rotate no worse, and in some cases even better, than a multi-bladed propeller. True, the direction of the moving medium should be tangential, which is not always possible or desirable in modern units, but the design is greatly simplified - it does not need blades at all. A gas turbine according to the Tesla scheme is not being built yet, but perhaps the idea is just waiting for its time.
circuit diagram
Now about the fundamental device of the machine. It is a combination of a rotating system mounted on an axis (rotor) and a fixed part (stator). On the shaft there is a disk with working blades forming a concentric lattice, they are affected by gas supplied under pressure through special nozzles. Then the expanded gas enters the impeller, also equipped with blades, called workers. For the inlet of the air-fuel mixture and the outlet (exhaust), special pipes are used. The compressor is also involved in the overall scheme. It can be made according to a different principle, depending on the required working pressure. For its operation, a part of the energy is taken from the axis, which is used to compress the air. The gas turbine works by means of the process of combustion of the air-fuel mixture, accompanied by a significant increase in volume. The shaft rotates, its energy can be used usefully. Such a scheme is called single-circuit, but if it is repeated, then it is considered multi-stage.
Advantages of aircraft turbines
Since about the mid-fifties, a new generation of aircraft has appeared, including passenger ones (in the USSR these are Il-18, An-24, An-10, Tu-104, Tu-114, Tu-124, etc.), in designs of which aircraft piston engines were finally and irrevocably supplanted by turbine ones. This indicates a greater efficiency of this type of power plant. The characteristics of the gas turbine are superior to the parameters of carbureted engines in many respects, in particular, in terms of power / weight, which is of paramount importance for aviation, as well as equally important indicators of reliability. Lower fuel consumption, fewer moving parts, better environmental performance, reduced noise and vibration. Turbines are less critical to fuel quality (which cannot be said about fuel systems), they are easier to maintain, they require less lubricating oil. In general, at first glance it seems that they do not consist of metal, but of solid virtues. Alas, it is not.
There are disadvantages of gas turbine engines
The gas turbine heats up during operation and transfers heat to the surrounding structural elements. This is especially critical, again in aviation, when using a redan layout scheme that involves washing the lower part of the tail unit with a jet stream. And the engine housing itself requires special thermal insulation and the use of special refractory materials that can withstand high temperatures.
Cooling gas turbines is a complex technical challenge. It's no joke, they work in the mode of a virtually permanent explosion occurring in the body. The efficiency in some modes is lower than that of carburetor engines, however, when using a dual-circuit scheme, this drawback is eliminated, although the design becomes more complicated, as in the case of including "booster" compressors in the scheme. Acceleration of turbines and reaching the operating mode requires some time. The more often the unit starts and stops, the faster it wears out.
Correct Application
Well, no system is without flaws. It is important to find such an application of each of them, in which its advantages will be more clearly manifested. For example, tanks such as the American Abrams, which is powered by a gas turbine. It can be filled with anything that burns, from high-octane gasoline to whiskey, and it puts out a lot of power. This may not be a very good example, as experience in Iraq and Afghanistan has shown the vulnerability of compressor blades to sand. Repair of gas turbines has to be done in the USA, at the manufacturing plant. Take the tank there, then back, and the cost of the maintenance itself, plus accessories ...
Helicopters, Russian, American and other countries, as well as powerful speedboats, are less affected by clogging. In liquid rockets, they are indispensable.
Modern warships and civilian ships also have gas turbine engines. And also energy.
Trigenerator power plants
The problems faced by aircraft manufacturers are not as worrying for those who make industrial equipment for generating electricity. Weight in this case is no longer so important, and you can focus on parameters such as efficiency and overall efficiency. Gas turbine generator units have a massive frame, a reliable frame and thicker blades. It is quite possible to utilize the generated heat, using it for a variety of needs, from secondary recycling in the system itself, to heating domestic premises and thermal supply of absorption-type refrigeration units. This approach is called trigenerator, and the efficiency in this mode approaches 90%.
Nuclear power plants
For a gas turbine, it makes no fundamental difference what is the source of the heated medium that gives its energy to its blades. It can be a burnt air-fuel mixture, or simply superheated steam (not necessarily water), the main thing is that it provides its uninterrupted power supply. In essence, the power plants of all nuclear power plants, submarines, aircraft carriers, icebreakers and some military surface ships (the Peter the Great missile cruiser, for example) are based on a gas turbine (GTU) rotated by steam. Safety and environmental issues dictate a closed primary loop. This means that the primary heat agent (in the first samples this role was played by lead, now it has been replaced by paraffin) does not leave the near-reactor zone, flowing around the fuel elements in a circle. The heating of the working substance is carried out in subsequent circuits, and the evaporated carbon dioxide, helium or nitrogen rotates the turbine wheel.
Wide application
Complex and large installations are almost always unique, their production is carried out in small batches or in general single copies are made. Most often, units produced in large quantities are used in peaceful sectors of the economy, for example, for pumping hydrocarbon raw materials through pipelines. It is these that are produced by the UEC company under the Saturn brand. Gas turbines of pumping stations are fully consistent with their name. They really pump natural gas, using its own energy for their work.
Gritsyna V.P.
In connection with the multiple growth of electricity tariffs in Russia, many enterprises are considering the construction of their own low-capacity power plants. In a number of regions, programs are being developed for the construction of small or mini thermal power plants, in particular, as a replacement for obsolete boiler houses. At a new small CHP plant with a fuel utilization rate of up to 90% with full use of the body in production and for heating, the cost of electricity received can be significantly lower than the cost of electricity received from the power grid.
When considering projects for the construction of small thermal power plants, power engineers and specialists of enterprises are guided by the indicators achieved in the large power industry. Continuous improvement of gas turbines (GTUs) for use in large-scale power generation has made it possible to increase their efficiency to 36% or more, and the use of a combined steam-gas cycle (CCGT) has increased the electrical efficiency of TPPs to 54% -57%.
However, in the small-scale power industry it is inappropriate to consider the possibility of using complex schemes of combined cycles of CCGT for the production of electricity. In addition, gas turbines, in comparison with gas engines, as drives for electric generators, lose significantly in terms of efficiency and performance, especially at low powers (less than 10 MW). Since in our country neither gas turbines nor gas piston engines have yet been widely used in small-scale stationary power generation, the choice of a specific technical solution is a significant problem.
This problem is also relevant for large-scale energy, i.e. for power systems. In modern economic conditions, in the absence of funds for the construction of large power plants on obsolete projects, which can already be attributed to the domestic project of a 325 MW CCGT, designed 5 years ago. Energy systems and RAO UES of Russia should pay special attention to the development of small-scale power generation, at whose facilities new technologies can be tested, which will make it possible to begin the revival of domestic turbine-building and machine-building plants and subsequently switch to large capacities.
In the last decade, large diesel or gas engine thermal power plants with a capacity of 100-200 MW have been built abroad. The electrical efficiency of diesel or gas engine power plants (DTPP) reaches 47%, which exceeds the performance of gas turbines (36%-37%), but is inferior to the performance of CCGTs (51%-57%). CCGT power plants include a large range of equipment: a gas turbine, a waste heat steam boiler, a steam turbine, a condenser, a water treatment system (plus a booster compressor if low or medium pressure natural gas is burned. Diesel generators can run on heavy fuel, which is 2 times cheaper than gas turbine fuel and can operate on low-pressure gas without the use of booster compressors.According to SEMT PIELSTICK, the total cost of operating a diesel power unit with a capacity of 20 MW over 15 years is 2 times less than for a gas turbine thermal power plant of the same capacity when using liquid fuel by both power plants.
A promising Russian manufacturer of diesel power units up to 22 MW is the Bryansk Machine-Building Plant, which offers customers power units with increased efficiency up to 50% for operation both on heavy fuel with a viscosity of up to 700 cSt at 50 C and a sulfur content of up to 5%, and for operation on gaseous fuel.
The option of a large diesel thermal power plant may be preferable to a gas turbine power plant.
In small-scale power generation, with unit capacities of less than 10 MW, the advantages of modern diesel generators are even more pronounced.
Let us consider three variants of thermal power plants with gas turbine plants and gas piston engines.
The fuel utilization factor for the first two options of power plants (with different electrical efficiency) due to heat supply can reach 80% -94%, both in the case of gas turbines and for motor drives.
The profitability of all variants of power plants depends on the reliability and efficiency, first of all, of the "first stage" - the drive of the electric generator.
Enthusiasts for the use of small gas turbines are campaigning for their widespread use, noting the higher power density. For example, in [1] it is reported that Elliot Energy Systems (in 1998-1999) is building a distribution network of 240 distributors in North America providing engineering and service support for the sale of "micro" gas turbines. The power grid ordered a 45 kW turbine to be ready for delivery in August 1998. It also stated that the electrical efficiency of the turbine was as high as 17%, and noted that gas turbines were more reliable than diesel generators.
This statement is exactly the opposite!
If you look at Table. 1. then we will see that in such a wide range from hundreds of kW to tens of MW, the efficiency of the motor drive is 13% -17% higher. The indicated resource of the motor drive of the company "Vyartsilya" means a guaranteed resource until a complete overhaul. The resource of new gas turbines is a calculated resource, confirmed by tests, but not by statistics of work in real operation. According to numerous sources, the resource of gas turbines is 30-60 thousand hours with a decrease with a decrease in power. The resource of diesel engines of foreign production is 40-100 thousand hours or more.
Table 1
Main technical parameters of electric generator drives
G-gas-turbine power plant, D-gas-piston generating plant of Vyartsilya.
D - diesel from the Gazprom catalog
* The minimum value of the required pressure of the fuel gas = 48 ATA!!
Performance characteristics
Electrical efficiency (and power) According to Värtsilä data, when the load is reduced from 100% to 50%, the efficiency of an electric generator driven by a gas engine changes little.
The efficiency of a gas engine practically does not change up to 25 °C.
The power of the gas turbine drops evenly from -30°C to +30°C.
At temperatures above 40 °C, the reduction in gas turbine power (from nominal) is 20%.
Start time gas engine from 0 to 100% load is less than a minute and emergency in 20 seconds. It takes about 9 minutes to start a gas turbine.
Gas supply pressure for a gas turbine it should be 16-20 bar.
The gas pressure in the network for a gas engine can be 4 bar (abs) and even 1.15 bar for a 175 SG engine.
Capital expenditures at a thermal power plant with a capacity of about 1 MW, according to Vartsila specialists, they amount to $1,400/kW for a gas turbine plant and $900/kW for a gas piston power plant.
Combined cycle application at small CHPPs, by installing an additional steam turbine is impractical, since it doubles the number of thermal and mechanical equipment, the area of the turbine hall and the number of maintenance personnel with an increase in power only 1.5 times.
With a decrease in the power of the CCGT from 325 MW to 22 MW, according to the NPP "Mashproekt" plant (Ukraine, Nikolaev), the front efficiency of the power plant decreases from 51.5% to 43.6%.
The efficiency of a diesel power unit (using gas fuel) with a capacity of 20-10 MW is 43.3%. It should be noted that in the summer at a CHPP with a diesel unit, hot water supply can be provided from the engine cooling system.
Calculations on the competitiveness of power plants based on gas engines showed that the cost of electricity at small (1-1.5 MW) power plants is approximately 4.5 cents / kWh), and at large 32-40 MW gas-powered plants 3, 8 US cents/kWh
According to a similar calculation method, electricity from a condensing nuclear power plant costs approximately 5.5 US cents/kWh. , and coal IES about 5.9 cents. US/kWh Compared to a coal-fired CPP, a plant with gas engines generates electricity 30% cheaper.
The cost of electricity produced by microturbines, according to other sources, is estimated at between $0.06 and $0.10/kWh
The expected price for a complete 75 kW gas turbine generator (US) is $40,000, which corresponds to the unit cost for larger (more than 1000 kW) power plants. The big advantage of power units with gas turbines is their smaller dimensions, 3 or more times less weight.
It should be noted that the unit cost of Russian-made electric generator sets based on automobile engines with a capacity of 50-150 kW may be several times less than the mentioned turbo blocks (USA), given the serial production of engines and the lower cost of materials.
Here is the opinion of Danish experts who evaluate their experience in the implementation of small power plants.
"Investment in a completed, turnkey natural gas CHP plant with a capacity of 0.5-40 MW is 6.5-4.5 million Danish krone per MW (1 krone was approximately equal to 1 ruble in the summer of 1998) Combined cycle CHP plants below 50 MW will achieve an electrical efficiency of 40-44%.
Operating costs for lubricating oils, Maintenance and the maintenance of personnel at CHPs reach 0.02 kroons per 1 kWh produced by gas turbines. At CHP plants with gas engines, operating costs are about 0.06 dat. kroons per 1 kWh. At current electricity prices in Denmark, the high performance of gas engines more than offsets their higher operating costs.
Danish specialists believe that most CHP plants below 10 MW will be equipped with gas engines in the coming years."
conclusions
The above estimates, it would seem, unambiguously show the advantages of a motor drive at low power of power plants.
However, at present, the power of the proposed Russian-made motor drive on natural gas does not exceed the power of 800 kW-1500 kW (RUMO plant, N-Novgorod and Kolomna Machine Plant), and several plants can offer turbo drives of higher power.
Two factories in Russia: plant im. Klimov (St. Petersburg) and Perm Motors are ready to supply complete power units of mini-CHP with waste heat boilers.
In the case of organizing a regional service center issues of maintenance and repair of small turbines of turbines can be solved by replacing the turbine with a backup one in 2-4 hours and its further repair in the factory conditions of the technical center.
The efficiency of gas turbines can currently be increased by 20-30% by applying power injection of steam into a gas turbine (STIG cycle or steam-gas cycle in one turbine). In previous years, this technical solution was tested in full-scale full-scale field tests of the Vodoley power plant in Nikolaev (Ukraine) by Mashproekt Research and Production Enterprise and Zarya Production Association, which made it possible to increase the power of the turbine unit from 16 to 25 MW and the efficiency was increased from 32 .8% to 41.8%.
Nothing prevents us from transferring this experience to smaller capacities and thus implementing a CCGT in serial delivery. In this case, the electrical efficiency is comparable to that of diesel engines, and the specific power increases so much that capital costs can be 50% lower than in a gas engine-driven CHP plant, which is very attractive.
This review was carried out in order to show: that when considering options for the construction of power plants in Russia, and even more so the directions for creating a program for the construction of power plants, it is necessary to consider not individual options that design organizations can offer, but a wide range of issues taking into account the capabilities and interests of domestic and regional manufacturers equipment.
Literature
1. Power Value, Vol.2, No.4, July/August 1998, USA, Ventura, CA.
The Small Turbine Marketplace
Stan Price, Northwest Energy Efficiency Council, Seattle, Washington and Portland, Oregon
2. New directions of energy production in Finland
ASKO VUORINEN, Assoc. tech. Sciences, Vartsila NSD Corporation JSC, "ENERGETIK" -11.1997. page 22
3. District heating. Research and development of technology in Denmark. Ministry of Energy. Energy Administration, 1993
4. DIESEL POWER PLANTS. S.E.M.T. PIELSTICK. POWERTEK 2000 Exhibition Prospectus, March 14-17, 2000
5. Power plants and electrical units recommended for use at the facilities of OAO GAZPROM. CATALOG. Moscow 1999
6. Diesel power station. Prospect of OAO "Bryansk Machine-Building Plant". 1999 Exhibition brochure POWERTEK 2000/
7. NK-900E Block-modular thermal power plant. OJSC Samara Scientific and Technical Complex named after V.I. N.D. Kuznetsova. Exhibition brochure POWERTEK 2000
Every now and then in the news they say that, for example, at such and such a state district power station, the construction of a CCGT unit of 400 MW is in full swing, and at another CHPP-2, a GTP installation of so many MW is put into operation. Such events are written about, they are covered, since the inclusion of such powerful and efficient units is not only a “tick” in the implementation state program, but also a real increase in the efficiency of power plants, the regional energy system and even the unified energy system.
But I would like to bring to your attention not about the implementation of state programs or forecast indicators, but about CCGT and GTU. In these two terms, not only the layman, but also the novice power engineer can get confused.
Let's start with the easier one.
GTU - gas turbine plant - is a gas turbine and an electric generator combined in one building. It is advantageous to install it at a thermal power plant. This is effective, and many CHP reconstructions are aimed at installing just such turbines.
Here is a simplified cycle of operation of a thermal plant:
Gas (fuel) enters the boiler, where it burns and transfers heat to water, which leaves the boiler in the form of steam and turns the steam turbine. The steam turbine turns the generator. We get electricity from the generator, and we take steam for industrial needs (heating, heating) from the turbine if necessary.
And in a gas turbine plant, the gas burns out and turns the gas turbine, which generates electricity, and the outgoing gases turn water into steam in the waste heat boiler, i.e. gas works with a double benefit: first it burns and turns the turbine, then it heats the water in the boiler.
And if the gas turbine plant itself is shown in even more detail, it will look like this:
This video clearly shows what processes take place in a gas turbine plant.
But it will be even more useful if the resulting steam is made to work - put it into a steam turbine so that another generator works! Then our GTU will become a STEAM-GAS UNIT (CCGT).
As a result, PSU is a broader concept. This plant is an independent power unit where fuel is used once and electricity is generated twice: in a gas turbine plant and in a steam turbine. This cycle is very efficient, and has an efficiency of about 57%! This is a very good result, which allows you to significantly reduce fuel consumption for obtaining a kilowatt-hour of electricity!
In Belarus, to increase the efficiency of power plants, gas turbines are used as a “superstructure” to the existing CHP scheme, and CCGTs are being built at state district power plants as independent power units. Working at power plants, these gas turbines not only increase the "forecast technical and economic indicators", but also improve the management of generation, as they have high maneuverability: speed of start-up and power gain.
That's how useful these gas turbines are!
In autonomous generation - small power generation in Lately considerable attention is given gas turbines different power. Power plants at the base gas turbines are used as the main or backup source of electricity and heat for industrial or domestic facilities. gas turbines as part of power plants are designed for operation in any climatic conditions of Russia. Areas of use gas turbines practically unlimited: oil and gas industry, industrial enterprises, structures housing and communal services.
Positive use factor gas turbines in the housing sector is that the content harmful emissions in exhaust gases, NO x and CO are at the level of 25 and 150 ppm, respectively (for reciprocating plants, these values are much higher), which allows you to install a power plant near residential areas. Usage gas turbines as power units of power plants avoids the construction of high chimneys.
Depending on the needs gas turbines equipped with steam or hot water waste heat boilers, which allows you to receive from the power plant either steam (low, medium, high pressure) for process needs, or hot water (DHW) with standard temperature values. You can get steam and hot water at the same time. The power of thermal energy produced by a power plant based on gas turbines, as a rule, is twice that of electricity.
At the power plant gas turbines in this configuration, the fuel efficiency increases to 90%. High usage efficiency gas turbines as power units is provided during long-term operation with maximum electrical load. With enough power gas turbines there is the possibility of combined use of steam turbines. This measure allows to significantly increase the efficiency of using the power plant, increasing the electrical efficiency up to 53%.
How much does a gas turbine power plant cost? What is its full price? What is included in the turnkey price?
Autonomous thermal power plant based on gas turbines has a lot of additional expensive, but often, just necessary equipment(a real-life example is a completed project). With the use of first-class equipment, the cost of a power plant of this level, on a turnkey basis, does not exceed 45,000 - 55,000 rubles per 1 kW of installed electric capacity. The final price of a power plant based on gas turbines depends on the specific tasks and needs of the consumer. The cost includes design, construction and commissioning. Gas turbines themselves, as power units, without additional equipment, depending on the manufacturer and power, cost from 400 to 800 dollars per 1 kW.
To obtain information on the cost of building a power plant or thermal power plant in your particular case, you must send a completed questionnaire to our company. After that, after 2-3 days, the customer-client receives a preliminary technical and commercial proposal - TCH (short example). Based on the TCH, the customer makes the final decision on the construction of a power plant based on gas turbines. As a rule, before making a decision, the client visits an existing facility in order to see a modern power plant with his own eyes and “touch everything with his hands”. Directly at the facility, the customer receives answers to existing questions.
The concept of block-modular construction is often taken as the basis for the construction of power plants based on gas turbines. Block-modular design provides high level factory readiness of gas turbine power plants and reduces the construction time for energy facilities.
Gas turbines - some arithmetic on the cost of energy produced
To produce 1 kW of electricity, gas turbines consume only 0.29–0.37 m³/h of gas fuel. When burning one cubic meter of gas, gas turbines generate 3 kW of electricity and 4–6 kW of thermal energy. With the price (averaged) for natural gas in 2011, 3 rubles. per 1 m³, the cost of 1 kW of electricity received from a gas turbine is approximately 1 ruble. In addition to this, the consumer receives 1.5–2 kW of free thermal energy!
With autonomous power supply from a power plant based on gas turbines, the cost of electricity and heat produced is 3–4 times lower than the tariffs in force in the country, and this does not take into account the high cost of connecting to state power grids (60,000 rubles per 1 kW in the Moscow region, 2011).
Construction of autonomous power plants based on gas turbines allows for significant savings Money by eliminating the costs of construction and operation of expensive power lines (TL), power plants based on gas turbines can significantly increase the reliability of electrical, heat supply as individual enterprises organizations or regions as a whole.
The degree of automation of the power plant based on gas turbines makes it possible to abandon a large number of maintenance personnel. During the operation of a gas power plant, only three people ensure its operation: an operator, an electrician on duty, and a mechanic on duty. When emergencies Reliable protection systems are provided to ensure the safety of personnel, the safety of systems and units of the gas turbine.
Atmospheric air is fed through an air intake equipped with a filter system (not shown in the diagram) to the inlet of a multistage axial compressor. The compressor compresses atmospheric air and delivers it at high pressure to the combustion chamber. At the same time, a certain amount of gas fuel is supplied to the combustion chamber of the turbine through the nozzles. Fuel and air mix and ignite. The air-fuel mixture burns, releasing a large amount of energy. The energy of the gaseous products of combustion is converted into mechanical work due to the rotation of the turbine blades by jets of hot gas. Part of the energy received is used to compress the air in the turbine compressor. The rest of the work is transferred to the electric generator through the drive axle. This work is the useful work of the gas turbine. Combustion products, which have a temperature of about 500-550 °C, are removed through the exhaust tract and turbine diffuser, and can be further used, for example, in a heat exchanger, to generate thermal energy.
Gas turbines, as engines, have the highest specific power among internal combustion engines, up to 6 kW/kg.
As a gas turbine fuel, kerosene, diesel fuel, gas can be used.
One of the advantages of modern gas turbines is a long life cycle - a motor resource (full up to 200,000 hours, before overhaul 25,000–60,000 hours).
Modern gas turbines are highly reliable. There is evidence of continuous operation of some units for several years.
Many gas turbine suppliers produce overhaul equipment on site, replacing individual components without transporting them to the manufacturing plant, which significantly reduces time costs.
The possibility of long-term operation in any power range from 0 to 100%, the absence of water cooling, operation on two types of fuel - all this makes gas turbines popular power units for modern autonomous power plants.
The use of gas turbines is most effective at medium power plants, and at capacities above 30 MW, the choice is obvious.