Who first described the principle of operation of a gas turbine. The principle of operation of GTU. What can be the resource of the installation before overhaul

The development of new types of gas turbines, the growing demand for gas compared to other types of fuel, large-scale plans of industrial consumers to create their own capacities cause a growing interest in gas turbine construction.

R The small generation market has great development prospects. Experts predict an increase in demand for distributed energy from 8% (currently) to 20% (by 2020). This trend is explained by the relatively low tariff for electricity (2-3 times lower than the tariff for electricity from the centralized network). In addition, according to Maxim Zagornov, a member of the general council of Delovaya Rossiya, president of the Association of small-scale power generation of the Urals, director of the MKS group of companies, small generation is more reliable than network: in the event of an accident on the external network, electricity supply does not stop. An additional advantage of decentralized energy is the speed of commissioning: 8-10 months, as opposed to 2-3 years for the creation and connection of network lines.

Denis Cherepanov, co-chairman of the Delovaya Rossiya committee on energy, claims that the future belongs to its own generation. According to Sergei Yesyakov, First Deputy Chairman of the State Duma Energy Committee, in the case of distributed energy in the energy-consumer chain, it is the consumer, not the energy sector, that is the decisive link. With its own generation of electricity, the consumer declares the necessary capacities, configurations and even the type of fuel, saving, at the same time, on the price of a kilowatt of energy received. Among other things, experts believe that additional savings can be obtained if the power plant operates in cogeneration mode: the utilized thermal energy will be used for heating. Then the payback period of the generating power plant will be significantly reduced.

The most actively developing area of ​​distributed energy is the construction of small-capacity gas turbine power plants. Gas turbine power plants are designed for operation in any climatic conditions as the main or backup source of electricity and heat for industrial and domestic facilities. The use of such power plants in remote areas allows you to get significant savings by eliminating the costs of building and operating long power lines, and in central areas - to increase the reliability of electrical and heat supply to both individual enterprises and organizations, and territories as a whole. Consider some gas turbines and gas turbine units that are offered by well-known manufacturers for the construction of gas turbine power plants in the Russian market.

General Electric

GE's wind turbine solutions are highly reliable and suitable for applications in a wide range of industries, from oil and gas to utilities. In particular, GE gas turbine units of the LM2500 family with a capacity of 21 to 33 MW and an efficiency of up to 39% are actively used in small generation. The LM2500 is used as a mechanical drive and a power generator drive, they work in power plants in simple, combined cycle, cogeneration mode, offshore platforms and pipelines.

For the past 40 years, GE turbines of this series have been the best-selling turbines in their class. In total, more than 2,000 turbines of this model have been installed in the world with a total operating time of more than 75 million hours.

Key features of the LM2500 turbines: lightweight and compact design for quick installation and easy maintenance; reaching full power from the moment of launch in 10 minutes; high efficiency (in a simple cycle), reliability and availability in its class; the possibility of using dual-fuel combustion chambers for distillate and natural gas; the possibility of using kerosene, propane, coke oven gas, ethanol and LNG as fuel; low NOx emissions using DLE or SAC combustion chambers; reliability factor - more than 99%; readiness factor - more than 98%; NOx emissions - 15 ppm (DLE modification).

To provide customers with reliable support throughout the life cycle of generating equipment, GE opened a specialized Energy Technology Center in Kaluga. It offers customers state-of-the-art solutions for the maintenance, inspection and repair of gas turbines. The company has implemented a quality management system in accordance with ISO 9001.

Kawasaki Heavy Industries

Japanese company Kawasaki Heavy Industries, Ltd. (KHI) is a diversified engineering company. An important place in its production program is occupied by gas turbines.

In 1943, Kawasaki created the first gas turbine engine in Japan and is now one of the world's recognized leaders in the production of gas turbines of small and medium power, having accumulated references for more than 11,000 installations.

With environmental friendliness and efficiency as a priority, the company has achieved great success in the development of gas turbine technologies and is actively pursuing promising developments, including in the field of new energy sources as an alternative to fossil fuels.

Having good experience in cryogenic technologies, technologies of production, storage and transportation of liquefied gases, Kawasaki conducts active research and development work in the field of hydrogen as a fuel.

In particular, the company already has prototypes of turbines that use hydrogen as an additive to methane fuel. In the future, turbines are expected, for which, much more energy-efficient and absolutely environmentally friendly, hydrogen will replace hydrocarbons.

GTU Kawasaki GPB series designed for baseload operation, including both parallel and isolated network interaction schemes, while the power range is based on machines from 1.7 to 30 MW.

In the model range there are turbines that use steam injection to suppress harmful emissions and use DLE technology modified by the company's engineers.

Electrical efficiency, depending on the generation cycle and power, respectively, from 26.9% for GPB17 and GPB17D (M1A-17 and M1A-17D turbines) to 40.1% for GPB300D (L30A turbine). Electric power - from 1700 to 30 120 kW; thermal power - from 13,400 to 8970 kJ / kWh; exhaust gas temperature - from 521 to 470°C; exhaust gas consumption - from 29.1 to 319.4 thousand m3/h; NOx (at 15% O2) - 9/15 ppm for gas turbines M1A-17D, M7A-03D, 25 ppm for turbine M7A-02D and 15 ppm for turbines L20A and L30A.

In terms of efficiency, Kawasaki gas turbines, each in its class, are either the world leader or one of the leaders. The overall thermal efficiency of power units in cogeneration configurations reaches 86-87%. The company produces a number of GTUs in dual-fuel (natural gas and liquid fuel) versions with automatic switching. At the moment, three models of gas turbines are most in demand among Russian consumers - GPB17D, GPB80D and GPB180D.

Kawasaki gas turbines are distinguished by: high reliability and long service life; compact design, which is especially attractive when replacing equipment of existing generating facilities; ease of maintenance due to the split design of the body, removable burners, optimally located inspection holes, etc., which simplifies inspection and maintenance, including by the user's personnel;

Environmental friendliness and economy. The combustion chambers of Kawasaki turbines are designed using the most advanced techniques to optimize the combustion process and achieve the best turbine efficiency, as well as reduce NOx and other harmful substances in the exhaust. Environmental performance is also improved through the use of advanced dry emission suppression technology (DLE);

Ability to use a wide range of fuels. Natural gas, kerosene, diesel fuel, type A light fuel oils, as well as associated petroleum gas can be used;

Reliable after-sales service. High level of service, including a free online monitoring system (TechnoNet) with reports and forecasts, technical support by highly qualified personnel, as well as trade-in replacement of a gas turbine engine during a major overhaul (GTU downtime is reduced to 2-3 weeks), etc. .d.

In September 2011, Kawasaki introduced a state-of-the-art combustion chamber system that lowers NOx emissions to less than 10 ppm for the M7A-03 gas turbine engine, even lower than current regulations require. One of the company's design approaches is to create new equipment that meets not only modern, but also future, more stringent, environmental performance requirements.

The highly efficient 5 MW GPB50D gas turbine with a Kawasaki M5A-01D turbine uses the latest proven technologies. The plant's high efficiency makes it optimal for electricity and cogeneration. Also, the compact design of the GPB50D is particularly advantageous when upgrading existing plants. The rated electrical efficiency of 31.9% is the best in the world among 5 MW plants.

The M1A-17D turbine, through the use of an original combustion chamber design with dry emission suppression (DLE), has excellent environmental performance (NOx< 15 ppm) и эффективности.

The ultra-low weight of the turbine (1470 kg), the lowest in the class, is due to the widespread use of composite materials and ceramics, from which, for example, the impeller blades are made. Ceramics are more resistant to operation at elevated temperatures, less prone to contamination than metals. The gas turbine has an electrical efficiency close to 27%.

In Russia, by now, Kawasaki Heavy Industries, Ltd. implemented a number of successful projects in cooperation with Russian companies:

Mini-TPP "Central" in Vladivostok

By order of JSC Far Eastern Energy Management Company (JSC DVEUK), 5 GTUs GPB70D (M7A-02D) were delivered for Tsentralnaya TPP. The station provides electricity and heat to consumers in the central part of the development of Russky Island and the campus of the Far Eastern Federal University. TPP Tsentralnaya is the first power facility in Russia with Kawasaki turbines.

Mini-CHP "Oceanarium" in Vladivostok

This project was also carried out by JSC "DVEUK" for power supply of the scientific and educational complex "Primorsky Oceanarium" located on the island. Two GPB70D gas turbines were delivered.

GTU manufactured by Kawasaki in Gazprom PJSC

Kawasaki’s Russian partner, MPP Energotekhnika LLC, based on the M1A-17D gas turbine, produces the Korvette 1.7K container power plant for installation in open areas with an ambient temperature range of -60 to + 40 °С.

Within the framework of the cooperation agreement, five EGTES KORVET-1.7K were developed and assembled at the production facilities of MPP Energotechnika. The areas of responsibility of the companies in this project were distributed as follows: Kawasaki supplies the M1A-17D gas turbine engine and turbine control systems, Siemens AG supplies the high-voltage generator. MPP Energotekhnika LLC manufactures a block container, an exhaust and air intake device, a power unit control system (including the SHUVGM excitation system), electrical equipment - main and auxiliary, completes all systems, assembles and supplies a complete power plant, and also sells APCS.

EGTES Korvet-1.7K has passed interdepartmental tests and is recommended for use at the facilities of Gazprom PJSC. The gas turbine power unit was developed by MPP Energotechnika LLC according to the terms of reference of PJSC Gazprom within the framework of the Scientific and Technical Cooperation Program of PJSC Gazprom and the Japan Natural Resources and Energy Agency.

Turbine for CCGT 10 MW at NRU MPEI

Kawasaki Heavy Industries Ltd. has manufactured and delivered a complete gas turbine plant GPB80D with a nominal power of 7.8 MW for the National Research University “MPEI” located in Moscow. CHP MPEI is a practical training and, generating electricity and heat on an industrial scale, provides them with the Moscow Power Engineering Institute itself and supplies them to the utility networks of Moscow.

Expansion of the geography of projects

Kawasaki, drawing attention to the advantages of developing local energy in the direction of distributed generation, proposed to start implementing projects using gas turbines of minimum capacity.

Mitsubishi Hitachi Power Systems

The model range of H-25 turbines is presented in the power range of 28-41 MW. The complete package of turbine production, including R&D and remote monitoring center, is carried out at the plant in Hitachi, Japan by MHPS (Mitsubishi Hitachi Power Systems Ltd.). Its formation falls on February 2014 due to the merger of the generating sectors of the recognized leaders in mechanical engineering Mitsubishi Heavy Industries Ltd. and Hitachi Ltd.

H-25 models are widely used around the world for both simple cycle operation due to high efficiency (34-37%), and combined cycle in 1x1 and 2x1 configuration with 51-53% efficiency. Having high temperature indicators of exhaust gases, the GTU has also successfully proven itself to operate in cogeneration mode with a total plant efficiency of more than 80%.

Many years of experience in the production of gas turbines for a wide range of capacities and a well-thought-out design of a single-shaft industrial turbine distinguish the N-25 with high reliability with an equipment availability factor of more than 99%. The total operating time of the model exceeded 6.3 million hours in the second half of 2016. The modern gas turbine is made with a horizontal axial split, which ensures its ease of maintenance, as well as the possibility of replacing parts of the hot path at the place of operation.

The countercurrent tubular-annular combustion chamber provides stable combustion on various types of fuel, such as natural gas, diesel fuel, liquefied petroleum gas, flue gases, coke oven gas, etc. pre-mixing of the gas-air mixture (DLN). The H-25 gas turbine engine is a 17-stage axial compressor coupled to a three-stage active turbine.

An example of reliable operation of the N-25 GTU at small generation facilities in Russia is the operation as part of a cogeneration unit for the own needs of the Ammoniy JSC plant in Mendeleevsk, the Republic of Tatarstan. The cogeneration unit provides the production site with 24 MW of electricity and 50 t/h of steam (390°C / 43 kg/cm3). In November 2017, the first inspection of the turbine combustion system was successfully carried out at the site, which confirmed the reliable operation of the machine components and assemblies at high temperatures.

In the oil and gas sector, N-25 GTUs were used to operate the Sakhalin II Onshore Processing Facility (OPF) site of the Sakhalin Energy Investment Company, Ltd. The OPF is located 600 km north of Yuzhno-Sakhalinsk in the landfall area of ​​the offshore gas pipeline and is one of the company's most important facilities responsible for preparing gas and condensate for subsequent transmission via pipeline to the oil export terminal and LNG plant. The technological complex includes four N-25 gas turbines, which have been in commercial operation since 2008. The cogeneration unit based on the N-25 GTU is maximally integrated into the OPF integrated power system, in particular, the heat from the exhaust gases of the turbine is used to heat crude oil for the needs of oil refining .

Siemens Industrial Gas Turbine Generator Sets (hereinafter referred to as GTU) will help to cope with the difficulties of the dynamically developing market of distributed generation. Gas turbines with a unit rated power from 4 to 66 MW fully meet the high requirements in the field of industrial combined energy production, in terms of plant efficiency (up to 90%), operational reliability, service flexibility and environmental safety, ensuring low life cycle costs and high return on investment. The experience of Siemens in the construction of industrial gas turbines and the construction of thermal power plants based on them has more than 100 years.

Siemens GTUs ranging from 4 to 66 MW are used by small utilities, independent power producers (eg industrial plants) and the oil and gas industry. The use of technologies for distributed generation of electricity with combined generation of thermal energy makes it possible to refuse from investing in many kilometers of power lines, minimizing the distance between the energy source and the facility that consumes it, and achieve serious cost savings by covering the heating of industrial enterprises and infrastructure facilities through heat recovery. A standard Mini-TPP based on a Siemens GTU can be built anywhere where there is access to a fuel source or its prompt supply.

SGT-300 is an industrial gas turbine with a rated electric power of 7.9 MW (see Table 1), which combines a simple, reliable design with the latest technology.

Table 1. Specifications of SGT-300 for Mechanical Drive and Power Generation

1) Electrical 2) Shaft mounted

Rice. 1. Structure of the SGT-300 gas generator

For industrial power generation, a single-shaft version of the SGT-300 gas turbine is used (see Fig. 1). It is ideal for combined heat and power (CHP) production. The SGT-300 gas turbine is an industrial gas turbine, originally designed for generation and has the following operational advantages for operating organizations:

Electrical efficiency - 31%, which is on average 2-3% higher than the efficiency of gas turbines of lower power, due to the higher efficiency value, an economic effect on fuel gas savings is achieved;

The gas generator is equipped with a low-emission dry combustion chamber using DLE technology, which makes it possible to achieve levels of NOx and CO emissions that are more than 2.5 times lower than those established by regulatory documents;

The GTP has good dynamic characteristics due to its single-shaft design and ensures stable operation of the generator in case of fluctuations in the load of the external connected network;

The industrial design of the gas turbine provides a long overhaul life and is optimal in terms of organizing service work that is carried out at the site of operation;

A significant reduction in the building footprint, as well as investment costs, including the purchase of plant-wide mechanical and electrical equipment, its installation and commissioning, when using a solution based on SGT-300 (Fig. 2).

Rice. 2. Weight and size characteristics of the SGT-300 block

The total operating time of the installed fleet of SGT-300 is more than 6 million hours, with the operating time of the leading GTU 151 thousand hours. Availability/availability ratio - 97.3%, reliability ratio - 98.2%.

OPRA (Netherlands) is a leading supplier of energy systems based on gas turbines. OPRA develops, manufactures and markets state-of-the-art gas turbine engines around 2 MW. The key activity of the company is the production of electricity for the oil and gas industry.

The reliable OPRA OP16 engine delivers higher performance at lower cost and longer life than any other turbine in its class. The engine runs on several types of liquid and gaseous fuels. There is a modification of the combustion chamber with a reduced content of pollutants in the exhaust. The OPRA OP16 1.5-2.0 MW power plant will be a reliable assistant in harsh operating conditions.

OPRA gas turbines are the perfect equipment for power generation in off-grid electric and small-scale cogeneration systems. The design of the turbine has been under development for more than ten years. The result is a simple, reliable and efficient gas turbine engine, including a low emission model.

A distinctive feature of the technology for converting chemical energy into electrical energy in OP16 is the COFAR patented fuel mixture preparation and supply control system, which provides combustion modes with minimal formation of nitrogen and carbon oxides, as well as a minimum of unburned fuel residues. The patented geometry of the radial turbine and the generally cantilever design of the replaceable cartridge, including the shaft, bearings, centrifugal compressor and turbine, are also original.

The specialists of OPRA and MES Engineering developed the concept of creating a unique unified technical complex for waste processing. Of the 55-60 million tons of all MSW generated in Russia per year, a fifth - 11.7 million tons - falls on the capital region (3.8 million tons - the Moscow region, 7.9 million tons - Moscow). At the same time, 6.6 million tons of household waste are removed from Moscow outside the Moscow Ring Road. Thus, more than 10 million tons of garbage settle in the Moscow region. Since 2013, out of 39 landfills in the Moscow Region, 22 have been closed. They should be replaced by 13 waste sorting complexes, which will be commissioned in 2018-2019, as well as four waste incineration plants. The same situation occurs in most other regions. However, the construction of large waste processing plants is not always profitable, so the problem of waste processing is very relevant.

The developed concept of a single technical complex combines fully radial OPRA plants with high reliability and efficiency with the MES gasification / pyrolysis system, which allows for the efficient conversion of various types of waste (including MSW, oil sludge, contaminated land, biological and medical waste, waste woodworking, sleepers, etc.) into an excellent fuel for generating heat and electricity. As a result of long-term cooperation, a standardized waste processing complex with a capacity of 48 tons / day has been designed and is under implementation. (Fig. 3).

Rice. 3. General layout of a standard waste processing complex with a capacity of 48 tons/day.

The complex includes a MES gasification unit with a waste storage site, two OPRA gas turbines with a total electrical power of 3.7 MW and a thermal power of 9 MW, as well as various auxiliary and protective systems.

The implementation of such a complex makes it possible on an area of ​​2 hectares to obtain an opportunity for autonomous energy and heat supply to various industrial and communal facilities, while solving the issue of recycling various types of household waste.

The differences between the developed complex and existing technologies stem from the unique combination of the proposed technologies. Small (2 t/h) volumes of consumed waste, along with a small required area of ​​the site, allow placing this complex directly near small settlements, industrial enterprises, etc., significantly saving money on the constant transportation of waste to their disposal sites. Complete autonomy of the complex allows you to deploy it almost anywhere. The use of the developed standard project, modular structures and the maximum degree of factory readiness of the equipment makes it possible to minimize the construction time to 1-1.5 years. The use of new technologies ensures the highest environmental friendliness of the complex. The MES gasification unit simultaneously produces gas and liquid fractions of fuel, and due to the dual-fuel nature of the OPRA GTU, they are used simultaneously, which increases fuel flexibility and reliability of power supply. The low demands of the OPRA GTU on fuel quality increase the reliability of the entire system. The MES unit allows the use of waste with a moisture content of up to 85%, therefore, waste drying is not required, which increases the efficiency of the entire complex. The high temperature of the exhaust gases of the OPRA GTU makes it possible to provide reliable heat supply with hot water or steam (up to 11 tons of steam per hour at 12 bar). The project is standard and scalable, which allows for the disposal of any amount of waste.

The calculations show that the cost of electricity generation will be from 0.01 to 0.03 euros per 1 kWh, which shows the high economic efficiency of the project. Thus, the OPRA company once again confirmed its focus on expanding the range of fuels used and increasing fuel flexibility, as well as focusing on the maximum use of "green" technologies in its development.

A turbine is any rotating device that uses the energy of a moving working fluid (fluid) to produce work. Typical turbine fluids are: wind, water, steam and helium. Windmills and hydroelectric power stations have used turbines for decades to turn electric generators and produce energy for industry and housing. Simple turbines have been known for much longer, the first of them appeared in ancient Greece.

In the history of power generation, however, gas turbines themselves appeared not so long ago. The first practical gas turbine started generating electricity in Neuchatel, Switzerland in 1939. It was developed by the Brown Boveri Company. The first gas turbine to power an aircraft also ran in 1939 in Germany, using a gas turbine designed by Hans P. von Ohain. In England in the 1930s, the invention and design of the gas turbine by Frank Whittle led to the first turbine-powered flight in 1941.

Figure 1. Scheme of an aircraft turbine (a) and a gas turbine for ground use (b)

The term "gas turbine" is easily misleading because for many it means a turbine engine that uses gas as fuel. In fact, a gas turbine (shown schematically in Figure 1) has a compressor that supplies and compresses gas (usually air); the combustion chamber, where the combustion of fuel heats the compressed gas and the turbine itself, which extracts energy from the flow of hot, compressed gases. This energy is enough to power the compressor and remains for useful applications. A gas turbine is an internal combustion engine (ICE) that uses the continuous combustion of fuel to produce useful work. In this, the turbine differs from carburetor or diesel internal combustion engines, where the combustion process is intermittent.

Since the use of gas turbines began in 1939 simultaneously in the power industry and in aviation, different names are used for aviation and land-based gas turbines. Aviation gas turbines are called turbojet or jet engines, and other gas turbines are called gas turbine engines. In English, there are even more names for these, in general, engines of the same type.

Use of gas turbines

In an aircraft turbojet, the energy from the turbine drives a compressor that draws air into the engine. The hot gas leaving the turbine is expelled into the atmosphere through the exhaust nozzle, which creates thrust. On fig. 1a shows a diagram of a turbojet engine.

Figure 2. Schematic representation of an aircraft turbojet engine.

A typical turbojet engine is shown in fig. 2. Such engines create thrust from 45 kgf to 45,000 kgf with a dead weight of 13 kg to 9,000 kg. The smallest engines drive cruise missiles, the largest - huge aircraft. The gas turbine in fig. 2 is a turbofan engine with a large diameter compressor. Thrust is created both by the air that is sucked in by the compressor and the air that passes through the turbine itself. The engine is large and capable of generating high thrust at low takeoff speeds, making it the most suitable for commercial aircraft. The turbojet engine does not have a fan and creates thrust with air that passes completely through the gas path. Turbojets have small frontal dimensions and produce the most thrust at high speeds, making them most suitable for use in fighter aircraft.

In non-aeronautical gas turbines, part of the energy from the turbine is used to drive the compressor. The remaining energy - "useful energy" is removed from the turbine shaft at an energy utilization device such as an electric generator or a ship's propeller.

A typical land based gas turbine is shown in fig. 3. Such installations can generate energy from 0.05 MW to 240 MW. The setup shown in fig. 3 is a gas turbine derived from the aircraft, but lighter. Heavier units are designed specifically for ground use and are called industrial turbines. Although aircraft-derived turbines are increasingly being used as primary power generators, they are still most commonly used as compressors for pumping natural gas, powering ships, and used as supplementary power generators during periods of peak demand. Gas turbine generators can turn on quickly, supplying energy when it is most needed.

Figure 3. The simplest, single-stage, land-based gas turbine. For example, in energy. 1 - compressor, 2 - combustion chamber, 3 - turbine.

The most important advantages of a gas turbine are:

1. It is able to generate a lot of power with a relatively small size and weight.
2. The gas turbine operates in a constant rotation mode, unlike reciprocating engines operating with constantly changing loads. Therefore, turbines last a long time and require relatively little maintenance.
3. Although the gas turbine is started using auxiliary equipment such as electric motors or another gas turbine, starting takes minutes. For comparison, the start-up time of a steam turbine is measured in hours.
4. A gas turbine can use a variety of fuels. Large land-based turbines typically use natural gas, while aviation turbines tend to use light distillates (kerosene). Diesel fuel or specially treated fuel oil can also be used. It is also possible to use combustible gases from the process of pyrolysis, gasification and oil refining, as well as biogas.
5. Typically, gas turbines use atmospheric air as the working fluid. When generating electricity, a gas turbine does not need a coolant (such as water).

In the past, one of the main disadvantages of gas turbines was their low efficiency compared to other internal combustion engines or steam turbines in power plants. However, over the past 50 years, improvements in their design have increased thermal efficiency from 18% in 1939 on a Neuchatel gas turbine to the current efficiency of 40% in simple cycle operation and about 55% in combined cycle (more on that below). In the future, the efficiency of gas turbines will increase even more, with efficiency expected to rise to 45-47% in the simple cycle and up to 60% in the combined cycle. These expected efficiencies are substantially higher than other common engines such as steam turbines.

Gas turbine cycles

The sequence diagram shows what happens when air enters, passes through the gas path and exits the gas turbine. Typically, a cyclogram shows the relationship between air volume and system pressure. On fig. 4a shows the Brayton cycle, which shows the change in the properties of a fixed volume of air passing through a gas turbine during its operation. The key areas of this cyclogram are also shown in the schematic representation of the gas turbine in fig. 4b.

Figure 4a. Brayton cycle diagram in P-V coordinates for the working fluid, showing the flows of work (W) and heat (Q).

Figure 4b. Schematic illustration of a gas turbine showing points from the Brayton cycle diagram.

The air is compressed from point 1 to point 2. The pressure of the gas increases while the volume of the gas decreases. The air is then heated at constant pressure from point 2 to point 3. This heat is produced by the fuel being introduced into the combustion chamber and burning continuously.

Hot compressed air from point 3 begins to expand between points 3 and 4. The pressure and temperature in this interval fall, and the volume of gas increases. In the engine in Fig. 4b, this is represented by the flow of gas from point 3 through the turbine to point 4. This produces energy that can then be used. In fig. 1a, the flow is directed from point 3" to point 4 through the outlet nozzle and produces thrust. "Useful work" in Fig. 4a is shown by curve 3'-4. This is the energy capable of driving the drive shaft of a ground turbine or creating thrust for an aircraft engine. Cycle Brighton ends in Fig. 4 with a process in which the volume and temperature of the air decrease as heat is released into the atmosphere.

Figure 5. Closed loop system.

Most gas turbines operate in an open cycle mode. In an open circuit, air is taken from the atmosphere (point 1 in Figs. 4a and 4b) and expelled back into the atmosphere at point 4, so the hot gas is cooled in the atmosphere after it is expelled from the engine. In a gas turbine operating in a closed cycle, the working fluid (liquid or gas) is constantly used to cool the exhaust gases (at point 4) in the heat exchanger (shown schematically in Fig. 5) and is sent to the compressor inlet. Since a closed volume with a limited amount of gas is used, a closed cycle turbine is not an internal combustion engine. In a closed cycle system, combustion cannot be sustained and the conventional combustion chamber is replaced by a secondary heat exchanger that heats the compressed air before it enters the turbine. The heat is provided by an external source, such as a nuclear reactor, a coal-fired fluidized-bed furnace, or other heat source. It was proposed to use closed-cycle gas turbines in flights to Mars and other long-term space flights.

A gas turbine that is designed and operated according to the Bryson cycle (Figure 4) is called a simple cycle gas turbine. Most gas turbines on aircraft operate on a simple cycle, as it is necessary to keep the weight and frontal dimension of the engine as small as possible. However, for land or sea use, it becomes possible to add additional equipment to the simple cycle turbine in order to increase the efficiency and/or power of the engine. Three types of modifications are used: regeneration, intermediate cooling and double heating.

Regeneration provides for the installation of a heat exchanger (recuperator) on the way of exhaust gases (point 4 in Fig. 4b). Compressed air from point 2 in fig. 4b is preheated on the heat exchanger by exhaust gases before entering the combustion chamber (Fig. 6a).

If the regeneration is well implemented, that is, the efficiency of the heat exchanger is high, and the pressure drop in it is small, the efficiency will be greater than with a simple turbine cycle. However, the cost of the regenerator should also be taken into account. The regenerators were used in gas turbine engines in the Abrams M1 tanks - the main battle tank of Operation Desert Storm - and in experimental gas turbine engines of vehicles. Gas turbines with regeneration increase efficiency by 5-6% and their efficiency is even higher when operating under partial load.

Intercooling also involves the use of heat exchangers. An intercooler (intercooler) cools the gas during its compression. For example, if the compressor consists of two modules, high and low pressure, an intercooler should be installed between them to cool the gas flow and reduce the amount of work required to compress in the high pressure compressor (Fig. 6b). The cooling agent can be atmospheric air (so-called air coolers) or water (eg sea water in a ship's turbine). It is easy to show that the power of a gas turbine with a well designed intercooler is increased.

double heating is used in turbines and is a way to increase the power output of a turbine without changing the operation of the compressor or increasing the operating temperature of the turbine. If the gas turbine has two modules, high and low pressure, then a superheater (usually another combustor) is used to reheat the gas flow between the high and low pressure turbines (Fig. 6c). It can increase the output power by 1-3%. Dual heating in aircraft turbines is realized by adding an afterburner at the turbine nozzle. This increases traction, but significantly increases fuel consumption.

Combined cycle gas turbine power plant is often abbreviated as CCGT. Combined cycle means a power plant in which a gas turbine and a steam turbine are used together to achieve greater efficiency than when used separately. The gas turbine drives an electric generator. Turbine exhaust gases are used to produce steam in a heat exchanger, this steam drives a steam turbine which also produces electricity. If steam is used for heating, the plant is called a cogeneration power plant. In other words, in Russia the abbreviation CHP (Heat and Power Plant) is commonly used. But at CHP plants, as a rule, not gas turbines work, but ordinary steam turbines. And the used steam is used for heating, so CHP and CHP are not synonymous. On fig. 7 is a simplified diagram of a cogeneration power plant, showing two heat engines installed in series. The top engine is a gas turbine. It transfers energy to the lower engine - the steam turbine. The steam turbine then transfers the heat to the condenser.

Figure 7. Diagram of a combined cycle power plant.

The efficiency of the combined cycle \(\nu_(cc) \) can be represented by a rather simple expression: \(\nu_(cc) = \nu_B + \nu_R - \nu_B \times \nu_R \) In other words, it is the sum of the efficiency of each of the stages minus their work. This equation shows why cogeneration is so efficient. Assume \(\nu_B = 40%\) is a reasonable upper bound for the efficiency of a Brayton cycle gas turbine. A reasonable estimate of the efficiency of a steam turbine operating on the Rankine cycle at the second stage of cogeneration is \(\nu_R = 30% \). Substituting these values ​​into the equation, we get: \(\nu_(cc) = 0.40 + 0.30 - 0.40 \times 0.3 = 0.70 - 0.12 = 0.58 \). That is, the efficiency of such a system will be 58%.

This is the upper bound for the efficiency of a cogeneration power plant. The practical efficiency will be lower due to the inevitable loss of energy between stages. Practically in the cogeneration systems put into operation in recent years, an efficiency of 52-58% has been achieved.

Gas turbine components

The operation of a gas turbine is best broken down into three subsystems: compressor, combustion chamber, and turbine, as shown in Fig. 1. Next, we will briefly review each of these subsystems.

Compressors and turbines

The compressor is connected to the turbine by a common shaft so that the turbine can turn the compressor. A single shaft gas turbine has a single shaft connecting the turbine and compressor. A two-shaft gas turbine (Fig. 6b and 6c) has two conical shafts. The longer one is connected to a low pressure compressor and a low pressure turbine. It rotates inside a shorter hollow shaft that connects the high pressure compressor to the high pressure turbine. The shaft connecting the turbine and high pressure compressor rotates faster than the shaft of the turbine and low pressure compressor. A three-shaft gas turbine has a third shaft connecting the turbine and the medium pressure compressor.

Gas turbines can be centrifugal or axial, or a combination. The centrifugal compressor, in which compressed air exits around the outer perimeter of the machine, is reliable, usually costs less, but is limited to a compression ratio of 6-7 to 1. They were widely used in the past and are still used today in small gas turbines.

In more efficient and productive axial compressors, compressed air exits along the axis of the mechanism. This is the most common type of gas compressor (see figures 2 and 3). Centrifugal compressors consist of a large number of identical sections. Each section contains a rotating wheel with turbine blades and a wheel with fixed blades (stators). The sections are arranged in such a way that the compressed air sequentially passes through each section, giving some of its energy to each of them.

Turbines have a simpler design than a compressor, since it is more difficult to compress the gas flow than to cause it to expand back. Axial turbines like those shown in fig. 2 and 3 have fewer sections than a centrifugal compressor. There are small gas turbines that use centrifugal turbines (with radial gas injection), but axial turbines are the most common.

The design and manufacture of a turbine is difficult because it is required to increase the lifetime of the components in the hot gas stream. The design reliability issue is most critical in the turbine's first stage, where temperatures are highest. Special materials and a sophisticated cooling system are used to make turbine blades that melt at a temperature of 980-1040 degrees Celsius in a gas stream whose temperature reaches 1650 degrees Celsius.

The combustion chamber

A successful combustion chamber design must satisfy many requirements, and its proper design has been a challenge since the days of the Whittle and von Ohin turbines. The relative importance of each of the requirements for the combustion chamber depends on the application of the turbine and, of course, some requirements conflict with each other. When designing a combustion chamber, compromises are inevitable. Most of the design requirements are related to the price, efficiency and environmental friendliness of the engine. Here is a list of basic requirements for a combustion chamber:

1. High fuel combustion efficiency under all operating conditions.
2. Low fuel underburning and carbon monoxide (carbon monoxide) emissions, low nitrogen oxide emissions under heavy load and no visible smoke emissions (minimization of environmental pollution).
3. Small pressure drop when gas passes through the combustion chamber. 3-4% pressure loss is a typical pressure drop.
4. Combustion must be stable in all modes of operation.
5. Combustion must be stable at very low temperatures and low pressure at high altitude (for aircraft engines).
6. Burning should be even, without pulsations or disruptions.
7. The temperature must be stable.
8. Long service life (thousands of hours), especially for industrial turbines.
9. Ability to use different types of fuel. Land turbines typically use natural gas or diesel fuel. For aviation kerosene turbines.
10. The length and diameter of the combustion chamber must match the size of the engine assembly.
11. The total cost of owning a combustion chamber should be kept to a minimum (this includes initial cost, operating and maintenance costs).
12. The combustion chamber for aircraft engines must have a minimum weight.

The combustion chamber consists of at least three main parts: shell, flame tube and fuel injection system. The shell must withstand the operating pressure and may be part of the gas turbine design. The shell closes a relatively thin-walled flame tube in which combustion and the fuel injection system take place.

Compared to other types of engines, such as diesel and reciprocating automobile engines, gas turbines produce the least amount of air pollutants per unit of power. Among gas turbine emissions, unburnt fuel, carbon monoxide (carbon monoxide), oxides of nitrogen (NOx) and smoke are of greatest concern. Although the contribution of aircraft turbines to total pollutant emissions is less than 1%, emissions directly into the troposphere doubled between 40 and 60 degrees north latitude, causing a 20% increase in ozone concentrations. In the stratosphere where supersonic aircraft fly, NOx emissions cause ozone depletion. Both effects harm the environment, so reducing nitrogen oxides (NOx) in aircraft engine emissions is what needs to happen in the 21st century.

This is a fairly short article that tries to cover all aspects of turbine applications, from aviation to energy, without relying on formulas. To get better acquainted with the topic, I can recommend the book "Gas Turbine in Railway Transport" http://tapemark.narod.ru/turbo/index.html. If you skip the chapters related to the specifics of the use of turbines on the railway, the book is still very understandable, but much more detailed.

A turbine is an engine in which the potential energy of a compressible fluid is converted into kinetic energy in the blade apparatus, and the latter in the impellers into mechanical work transmitted to a continuously rotating shaft.

Steam turbines by their design represent a heat engine that is constantly in operation. During operation, superheated or saturated water vapor enters the flow path and, due to its expansion, forces the rotor to rotate. Rotation occurs as a result of the steam flow acting on the blade apparatus.

The steam turbine is part of the steam turbine design, which is designed to generate energy. There are also installations that, in addition to electricity, can generate thermal energy - the steam that has passed through the steam blades enters the network water heaters. This type of turbine is called industrial-cogeneration or cogeneration type of turbines. In the first case, steam extraction is provided for industrial purposes in the turbine. Complete with a generator, a steam turbine is a turbine unit.

Steam turbine types

Turbines are divided, depending on the direction in which the steam moves, into radial and axial turbines. The steam flow in radial turbines is directed perpendicular to the axis. Steam turbines can be one-, two- and three-case. The steam turbine is equipped with a variety of technical devices that prevent the ingress of ambient air into the casing. These are a variety of seals, which are supplied with water vapor in a small amount.

A safety regulator is located on the front section of the shaft, designed to turn off the steam supply when the turbine speed increases.

Characteristics of the main parameters of the nominal values

· Turbine rated power- the maximum power that the turbine must develop for a long time at the terminals of the electric generator, with normal values ​​​​of the main parameters or when they change within the limits specified by industry and state standards. A controlled steam extraction turbine can develop power above its nominal power if this is in accordance with the strength conditions of its parts.

· Turbine economic power- the power at which the turbine operates with the greatest efficiency. Depending on the parameters of live steam and the purpose of the turbine, the rated power can be equal to the economic power or more by 10-25%.

· Nominal temperature of regenerative feed water heating- the temperature of the feed water downstream of the last heater in the direction of the water.

· Rated cooling water temperature- the temperature of the cooling water at the inlet to the condenser.

gas turbine(fr. turbine from lat. turbo swirl, rotation) is a continuous heat engine, in the blade apparatus of which the energy of compressed and heated gas is converted into mechanical work on the shaft. It consists of a rotor (blades mounted on disks) and a stator (guide vanes fixed in the housing).

Gas having a high temperature and pressure enters through the turbine nozzle apparatus into the low pressure area behind the nozzle part, simultaneously expanding and accelerating. Further, the gas flow enters the turbine blades, giving them part of its kinetic energy and imparting torque to the blades. The rotor blades transmit torque through the turbine discs to the shaft. Useful properties of a gas turbine: a gas turbine, for example, drives a generator located on the same shaft with it, which is the useful work of a gas turbine.

Gas turbines are used as part of gas turbine engines (used for transport) and gas turbine units (used at thermal power plants as part of stationary GTUs, CCGTs). Gas turbines are described by the Brayton thermodynamic cycle, in which air is first adiabatically compressed, then burned at constant pressure, and then adiabatically expanded back to starting pressure.

Types of gas turbines

- Aircraft and jet engines

- Auxiliary power unit

- Industrial gas turbines for electricity generation

- Turboshaft engines

- Radial gas turbines

- Microturbines

Mechanically, gas turbines can be considerably simpler than reciprocating internal combustion engines. Simple turbines may have one moving part: shaft/compressor/turbine/alternate rotor assembly (see image above), not including the fuel system.

More complex turbines (those used in modern jet engines) may have multiple shafts (coils), hundreds of turbine blades, moving stator blades, and an extensive system of complex piping, combustion chambers, and heat exchangers.

As a general rule, the smaller the motor, the higher the speed of the shaft(s) required to maintain the maximum linear speed of the blades. The maximum speed of the turbine blades determines the maximum pressure that can be reached, resulting in maximum power, regardless of engine size. The jet engine rotates at about 10,000 rpm and the micro-turbine at about 100,000 rpm.

The article describes how the efficiency of the simplest gas turbine is calculated, tables of different gas turbines and combined cycle plants are given to compare their efficiency and other characteristics.

In the field of industrial use of gas turbine and steam-gas technologies, Russia has lagged far behind the advanced countries of the world.

World leaders in the production of high-capacity gas and combined-cycle power plants: GE, Siemens Wistinghouse, ABB - achieved values ​​of unit power of gas turbine plants of 280-320 MW and an efficiency of over 40%, with a utilizing steam-power superstructure in a combined-cycle cycle (also called binary) - capacities of 430- 480 MW with efficiency up to 60%. If you have questions about the reliability of CCGT - then read the article.

These impressive figures serve as benchmarks in determining the development paths for the power engineering industry in Russia.

How is the efficiency of a gas turbine determined?

Here are a couple of simple formulas to show what the efficiency of a gas turbine plant is:

Turbine internal power:

• Nt = Gex * Lt, where Lt is the operation of the turbine, Gex is the flow rate of exhaust gases;

GTU internal power:

• Ni gtu \u003d Nt - Nk, where Nk is the internal power of the air compressor;

GTU effective power:

• Nef \u003d Ni gtu * Efficiency mech, efficiency mech - efficiency associated with mechanical losses in bearings, can be taken 0.99

Electric power:

• Nel \u003d Ne * efficiency eg, where efficiency eg is the efficiency associated with losses in the electric generator, we can take 0.985

Available heat of fuel:

• Qsp = Gtop * Qrn, where Gref - fuel consumption, Qrn - the lowest working calorific value of the fuel

Absolute electrical efficiency of a gas turbine plant:

• Efficiency \u003d Nel / Q dist

CCGT efficiency is higher than GTU efficiency since the combined-cycle plant uses the heat of the exhaust gases of the gas turbine. A waste heat boiler is installed behind the gas turbine, in which the heat from the exhaust gases of the gas turbine is transferred to the working fluid (feed water), the generated steam is sent to the steam turbine to generate electricity and heat.

Read also: How to choose a gas turbine plant for a CCGT plant

CCGT efficiency is usually represented by the ratio:

• PGU efficiency \u003d GTU efficiency * B + (1-GTU efficiency * B) * PSU efficiency

B is the degree of binarity of the cycle

Efficiency PSU - Efficiency of a steam power plant

• B = Qks/(Qks+Qku)

Qks is the heat of fuel burned in the combustion chamber of a gas turbine

Qku - heat of additional fuel burned in the waste heat boiler

At the same time, it is noted that if Qku = 0, then B = 1, i.e., the installation is completely binary.

Influence of the degree of binarity on the CCGT efficiency

Let's sequentially present the tables with the characteristics of the efficiency of gas turbines and after them the indicators of the CCGT with these gas engines, and compare the efficiency of a separate gas turbine and the efficiency of the CCGT.

Characteristics of modern powerful gas turbines

ABB gas turbines

Combined-cycle plants with ABB gas turbines

GE gas turbines

Read also: Why build Combined Cycle Thermal Power Plants? What are the advantages of combined cycle plants.

Combined-cycle plants with GE gas turbines

Siemens gas turbines

Combined-cycle plants with Siemens gas turbines

Westinghouse-Mitsubishi-Fiat gas turbines

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 fixed 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).

The classification of a gas turbine 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 the kinetic energy of the outflow jet. 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 producing 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 °C. 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 the future, the development of 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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