Gas turbine. Device and principle of operation. Industrial equipment. The principle of operation of gas turbine units (GTU) Purpose and design of a gas turbine

Power units - drives of electric generators for autonomous small thermal power plants can be diesel, gas piston, microturbine and gas turbine engines.

A large number of discussion and polemical articles have been written about the advantages of certain generating installations and technologies. As a rule, in disputes in the pen, either one or the other often remains in disgrace. Let's try to figure out why.

The defining criteria for choosing power units for the construction of autonomous power plants are the issues of fuel consumption, the level of operating costs, as well as the payback period of the power plant equipment.

Ease of operation, the level of maintenance and repairs, and the location where powertrain repairs are performed are important factors in the selection of power units. These issues are primarily related to the costs and problems that the owner of an autonomous power plant may have later.

In this article, the author does not have a selfish goal to prioritize in favor of piston or turbine technologies. The types of power plants of power plants are more correct, it is best to select directly to the project, based on individual conditions and terms of reference customer.

When choosing power equipment for the construction of an autonomous gas CHPP, it is advisable to consult with independent specialists from engineering companies already engaged in the construction of turnkey power plants. An engineering company must have completed projects, which you can see and visit with a guided tour. One should also take into account such a factor as the weakness and underdevelopment of the generating equipment market in Russia, the real sales volumes on which, in comparison with developed countries, are small and leave much to be desired - this, first of all, is reflected in the volume and quality of offers.

Gas Reciprocating Plants vs. Gas Turbine Engines - Operating Costs

Is it true that the operating costs of a mini-CHP with reciprocating machines are lower than the operating costs of a power plant with gas turbines?

Price overhaul a gas piston engine can make up 30–350% of the initial cost of the power unit itself, and not of the entire power plant - during overhaul, the piston group is replaced. Gas piston units can be repaired on site without complicated diagnostic equipment once every 7-8 years.

The cost of repairing a gas turbine unit is 30-50% of the initial investment. As you can see, the costs are roughly equal. Real, fair prices for the gas turbine and piston units themselves of comparable power and quality are also similar.

Due to its complexity, the overhaul of the gas turbine unit is not carried out on site. The supplier must take away the used unit and bring a replacement gas turbine unit. The old block can only be restored at the factory.

You should always take into account the observance of the routine maintenance schedule, the nature of the loads and the operating modes of the power plant, regardless of the type of installed power units.

The question, which is often exaggerated, about the finickyness of the turbine to operating conditions, is associated with outdated information from forty years ago. Then "on the ground", in the drive of power plants, aircraft turbines "removed from the wing" of the aircraft were used. Such turbines with minimal modifications were adapted to work as the main power units for power plants.

Today, modern autonomous power plants use industrial and industrial turbines designed for continuous operation with various loads.

The lower limit of the minimum electrical load, officially declared by manufacturing plants for industrial turbines, is 3-5%, but in this mode the fuel consumption increases by 40%. The maximum load of the gas turbine plant, in limited time intervals, can reach 110-120%.

Modern gas piston units have phenomenal efficiency, based on a high level of electrical efficiency. "Problems" associated with the operation of gas piston plants at low loads are resolved positively at the design stage. The design must be of high quality.

Compliance with the manufacturer's recommended operating mode will extend the life of engine parts, thus saving money for the owner of an autonomous power plant. Sometimes, in order to bring the gas piston machines to the nominal mode at partial loads, one or two electric boilers are included in the design of the thermal circuit of the station, which make it possible to provide the desired 50% of the load.

For power plants based on gas piston plants and gas turbines, it is important to comply with the N + 1 rule - the number of operating units plus one more for the reserve. “N + 1” is a convenient, rational number of installations for the operating personnel. This is due to the fact that for power plants of all types and types it is necessary to carry out routine maintenance and repair work.

An enterprise connected to the network can install only one installation and use its own electricity at cost, and during maintenance it can be powered from the mains, paying by the meter. This is cheaper than +1, but unfortunately not always feasible. This is due, as a rule, to the absence of an electrical network at all, or to the incredible high cost technical conditions on the connection itself.

Unscrupulous dealers of gas piston units and gas turbines, before the sale of equipment to the buyer, as a rule, provide only brochures - commercial literature general plan and very rarely - accurate information about the total operating costs and produced technical regulations.

On powerful gas piston units, oil does not need to be changed. At permanent work it is simply produced without having time to age. Oil on such installations is constantly topped up. Such operating modes are provided for by a special design of powerful gas piston engines and are recommended by the manufacturer.

Engine oil waste is 0.25–0.45 grams per kilowatt per hour produced. The waste is always higher when the load is reduced. As a rule, the set of a gas piston engine includes a special reservoir for continuous topping up of oil, and a mini-laboratory for checking its quality and determining the replacement period.

Accordingly, the oil filters or cartridges in them must also be replaced.

Since engine oil still burns out, piston units have a slightly higher level of harmful emissions into the atmosphere than gas turbine units. But since gas burns out completely and is one of the cleanest types of fuel, then talking about serious air pollution is just "blunt checkers". A couple of old Hungarian Ikarus buses are doing much more serious harm to the environment. To comply with environmental requirements, when using piston engines, it is necessary to build higher chimneys, taking into account the already existing level of MPC in the environment.

Waste oil from gas piston plants cannot be simply poured onto the ground - it needs to be disposed of - this is a "cost" for the owners of the power plant. But you can also make money on this - specialized organizations buy used engine oil.

Many of us use motor oil in our piston engines in cars. If the engine is in good working order, properly operated and filled with normal fuel, then no financial cataclysms associated with its consumption will occur.

The same is true at piston power plants: - there is no need to be afraid of the consumption of engine oil, it will not ruin you, with normal operation of modern high-quality gas piston plants, the costs for this item are only 2-3 (!) Kopecks per 1 kW of generated electricity.

In modern gas turbine installations, oil is used only in the gearbox. Its volume can be considered insignificant. Replacement of gear oil in gas turbines is carried out on average once every 3-5 years, and it is not required to top up.

To carry out the service in full, the complete set of a powerful gas piston installation must include a crane-beam. Heavy parts of piston engines are removed with the help of a crane-beam. The use of a girder crane requires high room ceilings for the engine rooms of the reciprocating power plant. For the repair of gas piston installations of low and medium power, you can get by with simpler lifting mechanisms.

On delivery, gas-piston power plants can be equipped with various repair tools and fixtures. Its presence suggests that even all critical operations can be performed by qualified personnel on site. Virtually all repairs to gas turbines can be carried out either at the manufacturing plant or with the direct assistance of factory specialists.

Replacement of spark plugs is required every 3-4 months. Replacing candles is only 1-2 (!) Kopecks in the cost of 1 kW / h of its own electricity.

Piston units, unlike gas turbine units, are liquid-cooled, so the personnel of an autonomous power plant must constantly monitor the level of the coolant and carry out periodic replacement, and if it is water, then it is necessary to carry out its chemical preparation.

The above features of the operation of piston units are absent in gas turbine units. Gas turbine units do not use such consumables and components as:

• engine oil,
• spark plug,
• oil filters,
• coolant,
• sets of high-voltage wires.

But the gas turbine cannot be repaired on site and the much higher gas consumption cannot be compared with the operating costs and consumables for piston units.

What to choose? Gas piston or gas turbine installations?

How does the power of power plants of power plants compare with the ambient temperature?

With a significant increase in ambient temperature, the power of the gas turbine plant decreases. But with a decrease in temperature, the electric power of a gas turbine plant, on the contrary, increases. Electric power parameters, according to existing ISO standards, are measured at t +15 ° C.

Sometimes important point is also the fact that a gas turbine unit is capable of giving 1.5 times more free heat energy than a piston unit of similar power. When using a powerful (from 50 MW) autonomous CHP plant in the municipal economy, for example, this can be of decisive importance when choosing the type of power units, especially with a large and uniform consumption of heat energy.

On the contrary, where heat is not required in large quantities, but an emphasis is needed on the production of electrical energy, it will be economically more expedient to use gas piston units.

The high temperature at the outlet of the gas turbine units makes it possible to use a steam turbine as part of a power plant. This equipment is in demand if the consumer needs to get the maximum amount of electrical energy with the same amount of gas fuel consumed, and thus achieve a high electrical efficiency - up to 59%. An energy complex of this configuration is more difficult to operate and costs 30-40% more than usual.

Power plants with steam turbines in their structure, as a rule, are designed for a fairly large capacity - from 50 MW and above.

Let's talk about the most important thing: gas piston plants versus gas turbine power units - efficiency

The efficiency of the power plant is more than relevant - it affects fuel consumption. The average specific consumption of gas fuel per 1 generated kW / h is much less for a gas piston installation, and at any load mode (although long-term loads of less than 25% are contraindicated for piston engines).

The electrical efficiency of piston machines is 40-44%, and of gas turbines - 23-33% (in the steam-gas cycle, the turbine is capable of delivering efficiency reaching 59%).

The combined cycle is used at high power plants - from 50-70 MW.

If you need to manufacture a locomotive, an airplane or a sea vessel, then one of the defining indicators is the efficiency (efficiency) of the power plant. The heat that is obtained during the operation of the engine of a locomotive, aircraft (or ship) is not used and is released into the atmosphere.

But we are not building a locomotive, but a power plant, and when choosing the type of power units for an autonomous power plant, the approach is somewhat different - here it is necessary to talk about the completeness of the use of combustible fuel - the fuel utilization factor (FUF).

Burning, the fuel performs the main work - it rotates the generator of the power plant. All the rest of the fuel combustion energy is heat that can and should be used. In this case, the so-called "overall efficiency", or rather the fuel utilization factor (FU) of the power plant will be about 80-90%.

If the consumer expects to use the thermal energy of an autonomous power plant in full, which is usually unlikely, then the coefficient of performance (COP) of an autonomous power plant is of no practical importance.

When the load is reduced to 50%, the electrical efficiency of the gas turbine decreases.

In addition, turbines require a high inlet gas pressure, and for this, compressors (reciprocating) must be installed and they also increase fuel consumption.
Comparison of gas turbine plants and gas piston engines as part of mini-CHP shows that the installation of gas turbines is advisable at facilities that have uniform electrical and heat needs with a power of over 30-40 MW.

From the above it follows that the electrical efficiency of power units different types has a direct projection on fuel consumption.

Gas piston units consume a quarter or even a third less fuel than gas turbine units - this is the main expense item!

Accordingly, with a similar or equal cost of the equipment itself, cheaper electrical energy is obtained on gas piston plants. Gas is the main consumable item in the operation of an autonomous power plant!

Gas piston units versus gas turbine engines - gas inlet pressure

Is it always necessary to have a high pressure gas pipeline when using gas turbines?

For all types of modern power plants of power plants, the pressure of the supplied gas is of no practical importance, since the gas turbine unit always contains a gas compressor, which is included in the cost of the power complex.

The compressor provides the required pressure performance of the gas fuel. Modern compressors are extremely reliable and low-maintenance units. In the world of modern technologies, both for gas piston engines and gas turbines, it is only important to have the proper volume of gas fuel to ensure normal work autonomous power plant.

However, it should not be forgotten that a booster compressor also requires a lot of energy, Supplies and service... Paradoxically, reciprocating compressors are often used for powerful turbines.

Gas Reciprocating Engines vs. Gas Turbine Units - Dual Fuel Plants

It is often written and said that dual-fuel installations can only be piston-type. Is it true?

This is not true. All well-known manufacturers of gas turbines have dual-fuel units in their range. The main feature of the dual-fuel plant is its ability to operate both on natural gas and diesel fuel. Due to the use of two types of fuel in a dual-fuel plant, a number of its advantages compared to mono-fuel plants can be noted:

• in the absence of natural gas, the unit automatically switches to operation on diesel fuel;
• during transient processes, the unit automatically switches to operation on diesel fuel.

Upon entering the operating mode, the reverse process of switching to operation on natural gas and diesel fuel is carried out;
Do not forget about the fact that the first turbines were originally designed to run on liquid fuel - kerosene.

Dual-fuel plants are still of limited use and are not needed for most autonomous CHP plants - there are simpler engineering solutions for this.

Gas piston units versus gas turbine units - number of starts

How many starts of gas piston units can be?

Number of starts: a gas piston engine can be started and stopped an unlimited number of times, and this does not affect its service life. But frequent starts and stops of gas piston units, with loss of power for their own needs, can lead to wear of the most loaded components (bearings of turbochargers, valves, etc.).

Due to the sharp changes in thermal stresses arising in the most critical units and parts of the hot section of the gas turbine unit during quick starts of the unit from a cold state, it is preferable to use a gas turbine unit for constant, continuous operation.

Gas piston engines of power plants versus gas turbine plants - resource before overhaul

What can be the resource of the installation before overhaul?

The service life of a gas turbine before overhaul is 40,000–60,000 working hours. With proper operation and timely maintenance of a gas piston engine, this indicator is also equal to 40,000–60,000 working hours. However, there are other situations when overhaul occurs much earlier.

Gas piston units versus gas turbine engines - capital investments and prices

What capital investments (investments) will be required in the construction of a power plant? What is the cost of building a turnkey autonomous power complex?

Calculations show that the investment (dollar / kW) in the construction of a thermal power plant with gas piston engines is approximately equal to that of gas turbine plants. Finnish thermal power plant WARTSILA with a capacity of 9 MW will cost the customer approximately 14 million euros. A similar gas turbine thermal power plant based on first-class turnkey units will cost $ 15.3 million.

Gas piston engines versus gas turbine plants - ecology

How are environmental requirements met?

It should be noted that gas piston units are inferior to gas turbine units in terms of NO x emissions. Since the engine oil burns out, piston units have a level of harmful emissions into the atmosphere slightly higher than that of gas turbine units.

But this is not critical: the SES requests the background level according to the MPC at the location of the mini-CHP. After that, the dispersion calculation is made so that the "addition" of harmful substances from the mini-CHP plant added to the background does not lead to an excess of the MPC. Through several iterations, the minimum chimney height is selected, at which the SanPiN requirements are met. The addition from the 16 MW plant in terms of NO x emissions is not so significant: at a chimney height of 30 m - 0.2 MPC, at 50 m - 0.1 MPC.

The level of harmful emissions from most modern gas turbine plants does not exceed 20-30 ppm, and in some projects this may have a certain value.

During operation, piston units have vibrations and low-frequency noise. Bringing noise to standard values ​​is possible, just the appropriate engineering solutions are needed. In addition to calculating the dispersion, when developing the section of the project documentation "Environmental Protection", an acoustic calculation is made and it is checked whether the selected design solutions and the materials used meet the requirements of SanPiN in terms of noise.

Any equipment emits noise in a specific frequency spectrum. Gas turbine installations have not passed this cup.

Gas Piston Plants vs. Gas Turbine Engines - Conclusions

With linear loads and compliance with the N + 1 rule, the use of gas piston engines as the main source of power supply is possible. As part of such a power plant, reserve units and tanks are required for storing the second type of fuel - diesel.

In the power range up to 40-50 MW, the use of piston motors at mini-CHP is considered absolutely justified.

In the case of using gas piston units, the consumer can completely get away from the external power supply, but only with a deliberate and balanced approach.

Piston units can also be used as backup or emergency sources of electricity.

A kind of alternative to piston units is gas microturbines. True, the prices for microturbines “bite” a lot and amount to ~ $ 2500-4000 per 1 kW of installed capacity!

Comparison of gas turbine plants and gas piston engines as part of mini-CHP shows that the installation of gas turbines is possible at any facilities that have electrical loads of more than 14-15 MW, but due to the high gas consumption, turbines are recommended for power plants of much higher power - 50-70 MW.

For many modern generating plants, 200,000 operating hours is not a critical value and, subject to the scheduled maintenance schedule and step-by-step replacement of turbine parts subject to wear: bearings, injectors, various auxiliary equipment (pumps, fans), the further operation of the gas turbine unit remains economically viable. High-quality gas piston units today also successfully overcome 200,000 operating hours.

This is confirmed by the current practice of operating gas turbine / gas piston units around the world.

When choosing the power units of an autonomous power plant, expert advice is needed!

Expert advice and supervision are also necessary in the construction of autonomous power plants. To solve the problem, you need an engineering company with experience and completed projects.

Engineering allows you to competently, unbiased and objectively determine the choice of the main and auxiliary equipment for the selection of the optimal configuration - the complete set of your future power plant.

Qualified engineering allows you to save significant money for the customer, which is 10–40% of the total cost. Engineering from power industry professionals avoids costly design and sourcing mistakes.

"Turbocharging", "turbojets", "turboprop" - these terms have become firmly established in the lexicon of 20th century engineers involved in the design and maintenance of vehicles and stationary electrical installations. They are used even in related fields and advertising, when they want to give a product name some hint of special power and efficiency. In aviation, missiles, ships and power plants, the most commonly used gas turbine. How does it work? Does it run on natural gas (as you might think from the name), 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 is made to answer these questions as fully as possible in this article.

Russian engineering leader UEC

Russia, unlike many other independent states that emerged after the collapse of the USSR, managed to largely preserve the machine-building industry. In particular, the company "Saturn" is engaged in the production of power plants for special purposes. 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 for 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 the device of the main products is at first glance simple. The accumulated experience is of great importance, allowing to take into account many technological subtleties, without which it is impossible to achieve 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 power engineering.

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 case.

It all started so simply ...

Searches and steam

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, a liquid flows from top to bottom, blades are placed in its flow. The wheel, equipped with them around the perimeter, turns. The windmill works the same way. Then came the age of steam, and the rotation of the wheel quickened. 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 operating on exactly this principle. In fact, it was the first gas turbine known to historical science (after all, steam is the gaseous aggregate state of water). Today, it is still customary to separate these two concepts. The invention of Heron was then reacted 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. Engineer Parsons worked in approximately the same direction, equipping his machine with several functionally connected stages.

Birth of gas turbines

A century earlier, a certain John Barber had a brilliant idea. Why heat the steam first? Isn't it easier to directly use the exhaust gas generated by 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 for use in a horseless carriage, but its elements are today used in modern rocket, aircraft tank and automobile engines. The beginning of the jet engine process was given in 1930 by Frank Whittle. He got the idea to use 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 an unconventional way. It seemed obvious to everyone that wheels with blades or blades "catch" the movement of the medium better than flat objects. Tesla, in his usual manner, proved that if a rotor system is assembled from disks, located on the axis in series, then due to the picking up of the boundary layers by the gas flow, it will rotate no worse, and in some cases even better than a multi-blade propeller. True, the directionality of the moving medium should be tangential, which is not always possible or desirable in modern units, but the design is significantly simplified - it does not need blades at all. A gas turbine according to the Tesla scheme is not yet being built, but perhaps the idea is just waiting for its time.

Schematic diagram

Now about the fundamental structure of the machine. It is a combination of a rotating system mounted on an axis (rotor) and a stationary part (stator). A disk with rotor blades forming a concentric lattice is placed on the shaft; they are exposed to gas supplied under pressure through special nozzles. Then the expanded gas enters the impeller, also equipped with blades, called working blades. For the intake of the air-fuel mixture and the exhaust (exhaust), special pipes are used. also in general scheme the compressor is involved. It can be made according to different principles, depending on the required working pressure. For its operation, part of the energy is taken from the axis, which goes to compress the air. A gas turbine operates by combustion of an air / fuel mixture, accompanied by a significant increase in volume. The shaft rotates, its energy can be used beneficially. Such a scheme is called single-circuit, but if it is repeated, then it is considered multi-stage.

The advantages of aircraft turbines

From about the mid-fifties, a new generation of aircraft appeared, including passenger aircraft (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 replaced by turbine ones. This indicates the greater efficiency of this type of power plant. The characteristics of a gas turbine surpass the parameters of carburetor engines in many respects, in particular, in terms of the power / weight ratio, which is of paramount importance for aviation, as well as in equally important indicators of reliability. Lower fuel consumption, fewer moving parts, better environmental performance, reduced noise and vibration. Turbines are less critical to the quality of fuel (which cannot be said about fuel systems), they are easier to maintain, and they do not require much lubricating oil. In general, at first glance it seems that they do not consist of metal, but of solid merits. Alas, this is not the case.

Gas turbine engines also have disadvantages

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 redirected layout scheme, which 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 technical challenge. It's no joke, they operate in the mode of an actually permanent explosion that occurs in the hull. The efficiency in some modes is lower than that of carburetor motors, however, when using a two-circuit circuit, this drawback is eliminated, although the design becomes more complicated, as in the case of including "booster" compressors in the circuit. The acceleration of the turbines and reaching the operating mode takes some time. The more often the unit starts and stops, the faster it wears out.

Correct application

Well, no system is complete without flaws. It is important to find such an application of each of them, in which its merits will be more clearly manifested. For example, tanks such as the American Abrams, which are powered by a gas turbine. It can be refueled with anything that burns, from high-octane gasoline to whiskey, and it delivers a lot of power. An example, perhaps not a very successful one, since the experience of use in Iraq and Afghanistan has shown the vulnerability of compressor blades to the effects of sand. Gas turbines have to be repaired in the USA, at a manufacturing plant. Take the tank there, then back, and the cost of the service itself, plus accessories ...

Helicopters, Russian, American and other countries, as well as powerful speedboats, suffer less from blockages. Liquid rockets 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 of less concern to those who make industrial equipment for power generation. Weight in this case is no longer so important, and you can focus on parameters such as efficiency and overall efficiency. Gas turbine generator sets have a massive frame, a reliable frame and thicker blades. The generated heat is quite possible to be utilized for a variety of needs, from secondary recycling in the system itself to heating. household premises and thermal power supply of refrigeration units of absorption type. This approach is called trigeneration, and the efficiency in this mode is close to 90%.

Nuclear power plants

For a gas turbine, it makes no fundamental difference what is the source of the heated medium, which gives its energy to its blades. It can be a burnt air-fuel mixture, or just superheated steam (not necessarily water), as long as it provides 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 are dictated by a closed primary circuit. This means that the primary thermal agent (in the first samples this role was played by lead, now it has been replaced by paraffin), does not leave the reactor zone, flowing around the fuel elements in a circle. The working substance is heated 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 series 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 hydrocarbons through pipelines. These are the very ones 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.

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 plants have used turbines for decades to power generators and generate energy for industry and housing. Simple turbines have been known for much longer, the first of which appeared in ancient Greece.

In the history of power generation, however, the actual gas turbines appeared not so long ago. The first practically usable 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 went into operation in 1939 in Germany, using a gas turbine developed by Hans P. von Ohine. In England in the 1930s, the invention and design of the gas turbine by Frank Whittle led to the first flight with a gas turbine engine in 1941.

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

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

Since the use of gas turbines began simultaneously in the energy sector and in aviation since 1939, different names are used for aviation and ground gas turbines. Aircraft gas turbines are called turbojet or jet engines, and other gas turbines are called gas turbine engines. IN English language there are even more names for these generally similar engines.

Using gas turbines

In an aircraft turbojet engine, turbine energy drives a compressor, which draws air into the engine. The hot gas leaving the turbine is discharged into the atmosphere through the exhaust nozzle, which creates a thrust force. In 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 45000 kgf with dead weight from 13 kg to 9000 kg. The smallest engines propel cruise missiles, the largest - huge planes. The gas turbine in Fig. 2 is a turbofan engine with a large diameter compressor. The thrust is also created by air, which is sucked in by the compressor, and air, which passes through the turbine itself. The engine is large and capable of generating high thrust at low speed during takeoff, which makes it most suitable for commercial aircraft. The turbojet does not have a fan and generates thrust with air that passes completely through the gas path. Turbojet engines have small frontal dimensions and produce the greatest thrust at high speeds, making them most suitable for use on fighters.

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

A typical gas turbine for land use is shown in Fig. 3. Such installations can generate energy from 0.05 MW to 240 MW. The installation shown in fig. 3 is a gas turbine derived from an aviation one, but lighter. Heavier units are designed specifically for ground use and are called industrial turbines. Although turbines derived from aircraft are increasingly used as primary power generators, they are still most commonly used as compressors to pump natural gas, power ships, and are used as supplemental power generators during peak periods. Gas turbine generators can be quickly put into operation, supplying energy at times of greatest need.

Figure 3. The simplest, one-stage, gas turbine for land use. For example, in the energy sector. 1 - compressor, 2 - combustion chamber, 3 - turbine.

The most important advantages of a gas turbine are:

1. It is capable of generating a lot of energy with a relatively small size and weight.
2. The gas turbine operates in a constant rotation mode, in contrast to reciprocating engines operating with constantly changing loads. Therefore, turbines have a long service life and relatively little maintenance.
3. Although the gas turbine is started with ancillary equipment such as electric motors or another gas turbine, it takes minutes to start. For comparison, the startup time of a steam turbine is measured in hours.
4. A gas turbine can use a variety of fuels. Large land-based turbines usually use natural gas, while aviation ones predominantly 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 pyrolysis process, gasification and oil refining, as well as biogas.
5. Usually gas turbines use atmospheric air as a working fluid. When generating electricity, a gas turbine does not need a refrigerant (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 the thermal efficiency from 18% in 1939 on a Neuchatel gas turbine to the current efficiency of 40% in a simple cycle and about 55% in a combined cycle (more on that below). In the future, the efficiency of gas turbines will increase even more, with efficiency in the simple cycle expected to rise to 45-47% and in the combined cycle to 60%. These expected efficiency values ​​are substantially higher than those of other common engines such as steam turbines.

Gas turbine cycles

The cyclogram shows what happens when air enters, passes through the gas path, and leaves the gas turbine. Typically, the cyclogram shows the relationship between air volume and system pressure. In fig. 4a shows the Brighton 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 sequence diagram are also shown in the gas turbine schematic in Fig. 4b.

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

Figure 4b. Gas turbine schematic showing points from the Brighton cycle diagram.

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

Hot compressed air from point 3 begins to expand between points 3 and 4. Pressure and temperature in this interval fall, and the volume of gas increases. In the engine in Fig. 4b, this is represented by the gas flow from point 3 to 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 that can drive a ground turbine drive shaft or create thrust for an aircraft engine. 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 circuit. In the open cycle, air is taken from the atmosphere (point 1 in Fig. 4a and 4b) and is thrown back into the atmosphere at point 4, so the hot gas is cooled in the atmosphere after being ejected from the engine. In a closed-cycle gas turbine, the working fluid (liquid or gas) is constantly used to cool the exhaust gases (at point 4) in a heat exchanger (shown schematically in Fig. 5) and is directed 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 up the compressed air before it enters the turbine. Heat is provided by an external source such as a nuclear reactor, fluidized bed coal fired 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 airplanes operate on a simple cycle in order to keep the weight and frontal dimensions of the engine as small as possible. However, for land or marine applications, it becomes possible to add additional equipment to the simple cycle turbine to increase the efficiency and / or power of the engine. Three types of modifications are used: regeneration, intercooling and double heating.

Regeneration provides for the installation of a heat exchanger (recuperator) in the path of the exhaust gases (point 4 in Fig. 4b). Compressed air from point 2 in Fig. 4b is preheated on a heat exchanger with 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 automobiles. Regenerated gas turbines increase efficiency by 5-6% and are even more efficient when operating at partial load.

Intermediate cooling also implies the use of heat exchangers. An intercooler (intercooler) cools the gas during compression. For example, if a compressor consists of two modules, high and low pressure, an intercooler must be installed between them to cool the gas flow and reduce the amount of work required to compress the compressor. high pressure(Fig.6b). The cooling agent can be ambient air (so-called air coolers) or water (for example, seawater in a ship's turbine). It is not difficult to show that the power of a gas turbine with a well-designed intercooler increases.

Double heating used in turbines and is a way to increase the power output of a turbine without altering compressor operation or increasing the operating temperature of the turbine. If the gas turbine has two modules, high and low pressure, then a superheater (usually another combustion chamber) is used to reheat the gas flow between the high and low pressure turbines (Figure 6c). This can increase the output power by 1-3%. Double 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 referred to as GHC. 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. A gas turbine drives an electric generator. The exhaust gases from the turbine are used to generate steam in a heat exchanger, this steam drives a steam turbine, which also produces electricity. If steam is used for heating, the installation is called a cogeneration power plant. In other words, in Russia, the abbreviation CHPP (combined heat and power plant) is usually used. But CHP plants, as a rule, do not operate gas turbines, but ordinary steam turbines. And the used steam is used for heating, so CHP and CHP are not synonymous. In fig. 7 is a simplified diagram of a cogeneration power plant, it shows two heat engines installed in series. The upper 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. Schematic 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 stage minus their product. This equation shows why cogeneration is so efficient. Suppose \ (\ nu_B = 40% \) is a reasonable upper efficiency estimate for a Brighton 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 estimate of the efficiency of a cogeneration power plant. Practical efficiency will be lower due to the inevitable loss of energy between steps. Practically in the systems of cogeneration of energy, 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 disassembled by dividing it into three subsystems: a compressor, a combustion chamber and a turbine, as is done 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 rotate 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 tapered 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 the high pressure compressor rotates faster than the shaft of the turbine and the low pressure compressor. The three-shaft gas turbine has a third shaft connecting the turbine and the medium pressure compressor.

Gas turbines can be of centrifugal or axial flow, or of a combined type. A centrifugal compressor, in which compressed air exits around the outside 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.

More efficient and efficient axial compressors expel compressed air along the axis of the machine. This is the most common type of gas compressor (see fig. 2 and 3). Centrifugal compressors are made up 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 passes through each section sequentially, giving part of its energy to each of them.

Turbines are of a simpler design than a compressor because it is more difficult to compress the gas stream than to cause it to expand backwards. Axial turbines similar to 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 flow turbines are the most common.

Turbine design and manufacture is challenging as it requires longer component life in the hot gas stream. The design reliability problem is most critical in the first stage of the turbine, where temperatures are highest. Special materials and a sophisticated cooling system are used to make the turbine blades 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 has to satisfy many requirements and proper design has been a challenge since the days of Whittle and von Ohain 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. There are inevitable trade-offs in combustion chamber design. Most of the design requirements are related to the price, efficiency and environmental friendliness of the engine. Here is a list of the basic requirements for a combustion chamber:

1. High efficiency of fuel combustion under all operating conditions.
2. Low emissions of undercooked fuel and carbon monoxide (carbon monoxide), low emissions of nitrogen oxides under heavy load and no visible smoke emissions (minimizing environmental pollution).
3. Low pressure drop when gas passes through the combustion chamber. A 3-4% pressure loss is a typical pressure drop.
4. Combustion must be stable under all operating conditions.
5. Combustion must be stable at very low temperatures and low pressure at high altitudes (for aircraft engines).
6. Burning should be smooth, without pulsations or breakdowns.
7. The temperature must be stable.
8. Long service life (thousands of hours), especially for industrial turbines.
9. The ability to use different types of fuel. Onshore turbines typically use natural gas or diesel. 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 ownership of the combustion chamber should be kept to a minimum (this includes initial cost, operating and repair costs).
12. The combustion chamber for aircraft engines must have a minimum weight.

The combustion chamber consists of at least three main parts: a shell, a flame tube and a fuel injection system. The shell must withstand the operating pressure and can be part of the gas turbine design. The shell covers 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 piston car engines, gas turbines produce the least amount of air pollutant emissions per unit of power. Among gas turbine emissions, the greatest concerns are unburned fuels, carbon monoxide (carbon monoxide), nitrogen oxides (NOx) and smoke. Although the contribution of aircraft turbines to total pollutant emissions is less than 1%, emissions directly into the troposphere have doubled between 40 and 60 degrees north latitude, causing an increase in ozone concentration of 20%. In the stratosphere, where supersonic aircraft fly, NOx emissions cause ozone destruction. Both effects are harmful to the environment, so reducing nitrogen oxides (NOx) in aircraft engine emissions is what must happen in the 21st century.

This is a fairly short article that tries to cover all aspects of turbine applications, from aviation to energy, and doesn't rely on formulas. To get a better understanding of the topic, I can recommend the book "Gas turbine on railway transport"Http://tapemark.narod.ru/turbo/index.html. If we omit the chapters related to the specifics of using turbines on the railway, the book is still very clear, but much more detailed.

A gas turbine, like a heat engine, combines the characteristics of a steam turbine and an internal combustion engine, in which the energy of the fuel is converted directly into mechanical work as it burns. The working fluid of gas turbines operating in an open cycle is the products of fuel combustion, and the working fluid of gas turbines operating in a closed cycle is clean air or gas continuously circulating in the system. On ships, gas turbine units (GTU) operating in an open cycle are used with fuel combustion at constant pressure (p = const) and GTU operating in a closed cycle.

Currently, marine gas turbines are of two types: 1) turbocompressor and 2) with free-piston gas generators (LNGG).

A diagram of the simplest turbocompressor gas turbine unit operating at a constant fuel combustion pressure is shown in Fig. 101. Compressor 9 sucks in clean atmospheric air, compresses it to high pressure and delivers it through the air duct3 into the combustion chamber 2, where at the same time through the nozzle1 fuel is supplied. Fuel, mixing with air, forms a working mixture, which burns out whenR = const. The resulting combustion products are cooled with air and sent to the turbine flow path. In stationary blades 4, the combustion products expand and at a high speed enter the rotor blades 5, where the kinetic energy of the gas flow is converted into mechanical work of shaft rotation. Through the branch pipe 6, the exhaust gases leave the turbine. The gas turbine drives the compressor 9 and through the gearbox7 propeller 8. To start the installation, a starting motor 10 is used, which spins the compressor to the minimum speed.

The same figure shows the theoretical cycle of the considered GTU in coordinates p -? andS - Т: АВ - the process of air compression in the compressor; BC-combustion of fuel at constant pressure in the combustion chamber; SD - gas expansion in the turbine, YES - heat removal from exhaust gases.

To increase the efficiency of the GTU operation, regenerative heating of the air entering the combustion chamber is used, or staged combustion of fuel in several successive combustion chambers that serve individual turbines. Due to its structural complexity, staged combustion is rarely used. In order to increase the effective efficiency of the unit, along with regeneration, two-stage air compression is used, while an air intercooler is included between the compressors, which reduces the required power of the high-pressure compressor.

In fig. 102 shows a diagram of the simplest gas turbine plant with fuel combustion atR = const and heat recovery. Compressed air in the compressor1 , passes through the regenerator 2 into the combustion chamber3 , where it is heated by the heat of the exhaust gases leaving the turbine 4 with a relatively high temperature. The actual cycle of this installation is shown in S-T diagram(fig. 103): Compressor air compression process1 - 2 ; heating of air in the regenerator, accompanied by a drop in pressure fromR 2 beforeR 4 2 - 3; heat supply in the process of fuel combustion 3 - 4; actual process of gas expansion in turbines4-5 ; cooling of gases in the regenerator, accompanied by a pressure loss p 5 -R 1 5-6; gas release - heat removal6-1 ... The amount of heat received by the air in the regenerator is represented by an area of ​​2 "-2-3-3", and the amount of heat given off by the exhaust gases in the regenerator is represented by an area of ​​6 "-6-5-5". These areas are equal to each other.

In a closed-cycle GTU, the spent working fluid does not enter the atmosphere, but after preliminary cooling it is again sent to the compressor. Consequently, a working fluid circulates in the cycle, which is not contaminated with combustion products. This improves the operating conditions of the turbine flow paths, as a result of which the reliability of the unit's operation increases and its service life increases. The combustion products do not mix with the working fluid and therefore any kind of fuel is suitable for combustion.

In fig. 104 shows a schematic diagram of an all-mode closed-cycle marine gas turbine plant. The air after pre-cooling in the air cooler 4 enters the compressor5 driven by a high-pressure turbine7 ... From the compressor the air is directed to the regenerator3 , and then into the air heater 6, which performs the same role as the combustion chamber in open-type installations. From the air heater, the working air at a temperature of 700 ° C enters the high-pressure turbine7 which rotates the compressor and then into the low pressure turbine2 which through the reducer1 drives an adjustable pitch screw. The starting electric motor 8 is designed to start the installation into operation. The disadvantages of a closed-cycle GTU include the bulkiness of the heat exchangers.

Of particular interest are closed-cycle gas turbines with a nuclear reactor. In these installations, helium, nitrogen, carbon dioxide are used as the working fluid of gas turbines (heat carrier). These gases are not activated in nuclear reactor... The gas heated in the reactor to a high temperature is sent directly to the gas turbine for operation.

The main advantages of gas turbines in comparison with steam turbines are: small weight and dimensions, since there is no boiler and condensing unit with auxiliary mechanisms and devices; quick start-up and development of full power within 10-15 minutes \ very low consumption of cooling water; ease of maintenance.

The main advantages of gas turbines in comparison with internal combustion engines are: the absence of a crank mechanism and associated inertial forces; small weight and dimensions at high power (gas turbine units are 2–2.5 times lighter in weight and 1.5–2 times shorter in length than diesel engines); the ability to work on low-grade fuel; lower operating costs. The disadvantages of gas turbines are as follows: short service life at high gas temperatures (for example, at a gas temperature of 1173 ° K, the service life is 500-1000 h); lower efficiency than diesel engines; significant noise during operation.

Currently, gas turbines are used as the main engines of marine transport vessels. In some cases, low-power gas turbines are used as a drive for pumps, emergency power generators, auxiliary supercharging compressors, etc. Gas turbines are of particular interest as main engines for hydrofoils and hovercraft.

Gritsyna V.P.

In connection with the multiple increase in electricity tariffs in Russia, many enterprises are considering the construction of their own small-capacity power plants. In a number of regions, programs are being developed for the construction of small or mini cogeneration plants, in particular, as a replacement for outdated boiler houses. At a new small CHPP, the fuel utilization rate at which reaches 90% with full use of the body in production and for heating, the cost of electricity generated can be significantly lower than the cost of electricity received from the power system.

When considering projects for the construction of small thermal power plants, power engineering specialists and specialists of enterprises are guided by the indicators achieved in the large power industry. Continuous improvement of gas turbines (GTU) for use in large-scale power engineering allowed increasing their efficiency to 36% or more, and the use of a combined steam-gas cycle (CCGT) increased the electrical efficiency of TPPs to 54% -57%.
However, in small-scale power engineering, it is inappropriate to consider the possibility of using complex schemes of combined cycles of CCGT for electricity generation. In addition, gas turbines, in comparison with gas engines, as drives of electric generators, are significantly inferior in terms of efficiency and operational characteristics, especially at low powers (less than 10 MW). Since in our country neither gas turbines nor gas piston engines have yet become widespread in small stationary power generation, the choice of a specific technical solution is a significant problem.
This problem is also relevant for large-scale power engineering, i.e. for power systems. In modern economic conditions, in the absence of funds for the construction of large power plants according to outdated projects, which can already include the domestic project of 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 the facilities of which new technologies can be tested, which will allow the revival of domestic turbine-building and machine-building plants to begin and in the future to move 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 electric efficiency of diesel or gas engine power plants (DTPP) reaches 47%, which exceeds the performance of gas turbine plants (36% -37%), but is inferior to the indicators of CCGT (51% -57%). CCGT power plants include a large range of equipment: a gas turbine, a steam waste heat 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 operate 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 the company SEMT PIELSTICK, the total cost for 15 years of operating a diesel power unit with a capacity of 20 MW is 2 times less than for a gas turbine TPP 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 an increased efficiency of 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 power plant may be preferable to a gas turbine power plant.
In small-scale power engineering with unit capacities less than 10 MW, the advantages of modern diesel generators are manifested to an even greater extent.
Consider three options for thermal power plants with gas turbine units and gas piston engines.

CHP, operating at rated load around the clock with waste heat boilers for heat supply or steam supply.

A CHP, an electric generator and a waste-heat boiler, which operate only during the day, and at night, heat is supplied from a hot water storage tank.

A thermal power plant that produces only electricity without using waste heat.

The fuel utilization ratio for the first two power plant options (with different electrical efficiency) due to heat supply can reach 80% -94%, both in the case of using gas turbines and for a motor drive.
The efficiency of all variants of power plants depends on the reliability and efficiency, first of all, of the "first stage" drive of the electric generator.
Small gas turbine enthusiasts are campaigning for their widespread use, noting their higher power density. For example, [1] reports that Elliot Energy Systems (1998-1999) is establishing a distribution network of 240 distributors in North America providing engineering and service support for the sale of "micro" gas turbines. The power system ordered the production of a 45 kW turbine, which was to be ready for delivery in August 1998. It also indicated that the electrical efficiency of the turbine reaches 17%, and notes that the reliability of gas turbines is higher than that of diesel generators.
This statement is exactly the opposite!
If you look at the 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 designated service life of the Vyartsilya motor drive means a guaranteed service life until complete overhaul. The resource of new gas turbines is an estimated 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 foreign-made diesel engines is 40-100 thousand hours or more.

Table 1
Main technical parameters of electric generator drives
G-gas turbine power plant, D-gas piston generator set Vyartsilya.
D - diesel from the Gazprom catalog
* The minimum value of the required fuel gas pressure = 48 ata !!
Performance characteristics
Electrical efficiency (and power) an electric generator driven by a gas engine according to Wärtsilä data when the load is reduced from 100% to 50%, the efficiency changes only slightly.
The efficiency of a gas engine practically does not change up to 25 ° C.
The power of the gas turbine decreases steadily from -30 ° C to +30 ° C.
At temperatures above 40 ° C, the decrease in the gas turbine power (from the nominal) is 20%.
Start time gas engine from 0 to 100% load is less than a minute and urgently 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 mains gas pressure for a gas engine can be 4 bar (abs) and even 1.15 bar for a 175 SG engine.
Capital expenditures at a combined heat and power plant with a capacity of about 1 MW, according to the estimates of Vyartsilya's specialists, they amount to $ 1400 / kW for a gas turbine 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 mechanical equipment, the area of ​​the turbine hall and the number service personnel with an increase in power only 1.5 times.
With a decrease in the capacity of the CCGT unit from 325 MW to 22 MW, according to the plant NPP "Mashproekt" (Ukraine, Nikolaev), the ceremonial efficiency of the power plant decreases from 51.5% to 43.6%.
The efficiency of a diesel power unit (fueled with gas) with a capacity of 20-10 MW is 43.3%. It should be noted that in the summertime 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 with gas engines, stations 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 the coal IES is about 5.9 cents. US / kWh Compared to a coal-fired IES, a gas-fired power plant generates electricity 30% cheaper.
The cost of electricity generated by microturbines, according to other data, is estimated in the range from $ 0.06 to $ 0.10 / kWh
The expected price for a complete US 75 kW gas turbine generator is $ 40,000, which corresponds to the unit cost for larger (over 1000 kW) power plants. The big advantage of power units with gas turbines is their smaller dimensions, 3 or more times less weight.
Note that the specific cost of generating sets Russian production based on automobile engines with a capacity of 50-150 kW may turn out to be several times less than the aforementioned turbine blocks (USA), given the serial production of engines and the lower cost of materials.
Here is the opinion of Danish experts assessing their experience in the implementation of small power plants.
"Investments in a completed, turnkey natural gas CHP plant with a capacity of 0.5-40 MW is 6.5-4.5 million DKK per MW (1 crown was approximately equal to 1 ruble in the summer of 1998) A combined cycle CHP plant with a capacity below 50 MW will achieve an electrical efficiency of 40-44%.
Operating costs for lubricating oils, Maintenance and the maintenance of personnel at the CHP plant reaches 0.02 kroons per 1 kWh produced by gas turbines. In a CHP plant with gas engines, operating costs are around 0.06 dates. CZK for 1 kWh At current electricity prices in Denmark, the high performance of gas engines more than compensates for their higher operating costs.
Danish experts believe that most of the CHPPs with a capacity 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 the motor drive at low 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 Kolomensky machine plant), and several factories can offer higher power turbo drives.
Two factories in Russia: zd im. Klimova (St. Petersburg) and Permskie Motory are ready to supply complete power units for mini-CHPPs with waste heat boilers.
In the case of organizing a regional service center, the issues of maintenance and repair of small turbines of turbines can be solved by replacing the turbine with a reserve 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 using power injection of steam into a gas turbine (STIG cycle or combined cycle gas cycle in one turbine). This technical solution has been tested in full-scale field tests in previous years. power plant"Vodoley" in Nikolaev (Ukraine) NPP "Mashproekt" and PA "Zarya", which allowed increasing the capacity of the turbine unit from 16 to 25 MW and efficiency was increased from 32.8% to 41.8%.
Nothing prevents to transfer this experience to lower capacities and thus realize the CCGT in serial delivery. In this case, the electric efficiency is compared to that of diesel engines, and the power density increases so much that capital costs can be 50% lower than in a CHP with a gas engine drive, 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 may be proposed by design organizations, but a wide list 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, JSC Vyartsila NSD Corporation, "ENERGETIK" -11.1997. page 22
3. District heating. Research and development of technology in Denmark. Department of Energy. Energy Directorate, 1993
4. DIESEL POWER PLANTS. S.E.M.T. PIELSTICK. POWERTEK 2000 exhibition brochure, March 14-17, 2000
5. Power plants and electrical units recommended for use at the facilities of JSC "GAZPROM". CATALOG. Moscow 1999
6. Diesel power plant. Prospectus of JSC "Bryansk Machine-Building Plant". 1999 POWERTEK 2000 exhibition brochure /
7. NK-900E Block-modular thermal power plant. JSC Samara Scientific and Technical Complex named after N. D. Kuznetsova. POWERTEK 2000 exhibition brochure