Construction of gas turbines. Gas turbines are reliable power units of modern power plants. Use of gas turbines

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

In the field of industrial use of gas turbine and combined cycle technologies, Russia is significantly behind the advanced countries of the world.

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

These impressive figures serve as guidelines in determining the development paths for the Russian power engineering industry.

How is the efficiency of a gas turbine unit determined?

Let's give a couple of simple formulas to show what efficiency is gas turbine unit:

Turbine internal power:

• Nт = Gух * Lт, where Lт – turbine operation, Gух – exhaust gas flow rate;

Internal power of gas turbine unit:

• Ni gtu = Nt – Nk, where Nk is the internal power of the air compressor;

Effective power of the gas turbine unit:

• Neph = Ni gtu * efficiency mech, efficiency mech – efficiency associated with mechanical losses in bearings, 0.99 can be taken

Electric power:

• Nel = Ne * Eg efficiency, where Eg efficiency is the efficiency associated with losses in the electric generator, we can take 0.985

Available fuel heat:

• Q run = Gtop * Qrn, where Gtop is fuel consumption, Qrn is the lower working heat of fuel combustion

Absolute electrical efficiency of a gas turbine unit:

• Efficiency = Nel/Q disp

CCGT efficiency is higher than GTU efficiency since the steam-gas plant uses the heat of the exhaust gases of the gas turbine unit. A waste heat boiler is installed behind the gas turbine in which 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 unit for a station with a CCGT unit

The efficiency of a CCGT unit is usually represented by the ratio:

• PSU efficiency = GTU efficiency*B+(1-GTU efficiency*B)*PSU efficiency

B – degree of binarity of the cycle

PSU efficiency - steam power plant efficiency

• B = Qks/(Qks+Qku)

Qкс – heat of fuel burned in the combustion chamber of a gas turbine

Qку – heat of additional fuel burned in the waste heat boiler

It is noted that if Qky = 0, then B = 1, i.e. the installation is completely binary.

Influence of the degree of binarity on the efficiency of CCGT units

B	GTU efficiency	Dog efficiency	PGU efficiency
1	0,32	0,3	0,524
1	0,36	0,32	0,565
1	0,36	0,36	0,590
1	0,38	0,38	0,612
0,3	0,32	0,41	0,47
0,4	0,32	0,41	0,486
0,3	0,36	0,41	0,474
0,4	0,36	0,41	0,495
0,3	0,36	0,45	0,51
0,4	0,36	0,45	0,529

Let's present sequentially the tables with the efficiency characteristics of the gas turbine unit and, after them, the performance of the combined cycle gas turbine units with these gas machines, and compare the efficiency of an individual gas turbine unit and the efficiency of the combined cycle gas turbine unit.

Characteristics of modern powerful gas turbines

ABB gas turbines

Characteristic	GTU model
	GT26GTU with reheating	GT24GTU with reheating
Power ISO MW	265	183
Efficiency %	38,5	38,3
	30	30
	562	391
	1260	1260
	610	610
	50	50

Combined-cycle plants with ABB gas turbines

GE gas turbines

Characteristic	GTU model
	MS7001FA	MS9001FA	MS7001G	MS9001G
Power ISO MW	159	226,5	240	282
Efficiency %	35,9	35,7	39,5	39,5
Compressor pressure ratio	14,7	14,7	23,2	23,2
Working fluid flow rate at gas turbine exhaust kg/s	418	602	558	685
Initial temperature, in front of the working blades 1 tbsp. WITH	1288	1288	1427	1427
Temperature of the working fluid at the exhaust C	589	589	572	583
Generator rotation frequency 1/s	60	50	60	50

Read also: Why build combined cycle thermal power plants? What are the advantages of combined cycle gas plants.

Combined-cycle plants with GE gas turbines

Characteristic	GTU model
	MS7001FA	MS9001FA	MS7001G	MS9001G
Composition of the gas turbine part of the CCGT unit	1xMS7001FA	1xMS9001FA	1xMS9001G	1xMS9001H
CCGT model	S107FA	S109FA	S109G	S109H
CCGT power MW	259.7	376.2	420.0	480.0
CCGT efficiency %	55.9	56.3	58.0	60.0

Gas turbines from Siemens

Characteristic	GTU model
	V64.3A	V84.3A	V94.3A
Power ISO MW	70	170	240
Efficiency %	36,8	38	38
Compressor pressure ratio	16,6	16,6	16,6
Working fluid flow rate at gas turbine exhaust kg/s	194	454	640
Initial temperature, in front of the working blades 1 tbsp. WITH	1325	1325	1325
Temperature of the working fluid at the exhaust C	565	562	562
Generator rotation frequency 1/s	50/60	60	50

Combined-cycle plants with Siemens gas turbines

Westinghouse-Mitsubishi-Fiat gas turbines

Characteristic	GTU model
	501F	501G	701F	701G1	701G2
Power ISO MW	167	235,2	251,1	271	308
Efficiency %	36,1	39	37	38,7	39
Compressor pressure ratio	14	19,2	16,2	19	21
Working fluid flow rate at gas turbine exhaust kg/s	449,4	553,4	658,9	645	741
Initial temperature, in front of the working blades 1 tbsp. WITH	1260	1427	1260	1427	1427
Temperature of the working fluid at the exhaust C	596	590	569	588	574
Generator rotation frequency 1/s	60	60	50	50	50

A traditional modern gas turbine unit (GTU) is a combination of an air compressor, a combustion chamber and a gas turbine, as well as auxiliary systems that ensure its operation. The combination of a gas turbine unit and an electric generator is called a gas turbine unit.

It is necessary to emphasize one important difference between GTU and PTU. The PTU does not include a boiler; more precisely, the boiler is considered as a separate heat source; with this consideration, the boiler is a “black box”: feed water enters it with a temperature of $t_(p.v)$, and steam exits with the parameters $р_0$, $t_0$. A steam turbine plant cannot operate without a boiler as a physical object. In a gas turbine unit, the combustion chamber is its integral element. In this sense, the GTU is self-sufficient.

Gas turbine plants are extremely diverse, perhaps even more diverse than steam turbine plants. Below we will consider the most promising and most used simple cycle gas turbine plants in the energy sector.

Schematic diagram such a gas turbine unit is shown in the figure. Air from the atmosphere enters the inlet of an air compressor, which is a rotary turbomachine with a flow path consisting of rotating and stationary gratings. Pressure ratio downstream of compressor p b to the pressure in front of him p a is called the compression ratio of an air compressor and is usually denoted as pk (pk = p b/p a). The compressor rotor is driven by a gas turbine. A stream of compressed air is supplied to one, two or more combustion chambers. In most cases, the air flow coming from the compressor is divided into two streams. The first flow is directed to the burner devices, where fuel (gas or liquid fuel) is also supplied. When fuel is burned, high-temperature fuel combustion products are formed. Relatively cold air from the second stream is mixed with them in order to obtain gases (usually called working gases) with a temperature acceptable for the gas turbine parts.

Working gases with pressure r s (r s < p b due to the hydraulic resistance of the combustion chamber) are fed into the flow part of a gas turbine, the principle of operation of which is no different from the principle of operation of a steam turbine (the only difference is that the gas turbine operates on fuel combustion products, and not on steam). In a gas turbine, the working gases expand to almost atmospheric pressure p d, enter the output diffuser 14, and from it - either directly into the chimney, or first into some heat exchanger that uses the heat of the exhaust gases of the gas turbine plant.

Due to the expansion of gases in a gas turbine, the latter produces power. A very significant part of it (about half) is spent on driving the compressor, and the remaining part on driving the electric generator. This is the useful power of the gas turbine unit, which is indicated when it is labeled.

To depict gas turbine circuits, use symbols, similar to those used for vocational schools.

A gas turbine cannot be simpler, since it contains a minimum of necessary components that ensure sequential processes of compression, heating and expansion of the working fluid: one compressor, one or more combustion chambers operating under the same conditions, and one gas turbine. Along with simple cycle gas turbine plants, there are complex cycle gas turbine plants, which can contain several compressors, turbines and combustion chambers. In particular, gas turbines of this type include the GT-100-750, built in the USSR in the 70s.

It is made of two shafts. The high pressure compressor is located on one shaft KVD and the high-pressure turbine driving it theater of operations; this shaft has a variable rotation speed. The low pressure turbine is located on the second shaft TND, driving the low pressure compressor KND and electric generator EG; therefore this shaft has a constant rotation speed of 50 s -1. Air in an amount of 447 kg/s comes from the atmosphere into KND and is compressed in it to a pressure of approximately 430 kPa (4.3 at) and then fed into the air cooler IN, where it is cooled with water from 176 to 35 °C. This reduces the work required to compress air in a high-pressure compressor KVD(compression ratio p k = 6.3). From it, air enters the high-pressure combustion chamber KSWD and combustion products with a temperature of 750 °C are sent to theater of operations. From theater of operations gases containing significant amounts of oxygen enter the low-pressure combustion chamber KSND, in which additional fuel is burned, and from it into TND. Exhaust gases at a temperature of 390 °C exit either into the chimney or into a heat exchanger to use the heat of the flue gases.

Gas turbines are not very economical due to the high temperature of the exhaust gases. Increasing the complexity of the scheme makes it possible to increase its efficiency, but at the same time requires increased capital investment and complicates operation.

The figure shows the device of the Siemens V94.3 gas turbine unit. Atmospheric air from an integrated air purification device (ACP) enters the mine 4 , and from it - to the flow part 16 air compressor. The compressor compresses air. The compression ratio in typical compressors is pc = 13-17, and thus the pressure in the gas turbine unit does not exceed 1.3-1.7 MPa (13-17 at). This is another serious difference between a gas turbine and a steam turbine, in which the steam pressure is 10-15 times greater than the gas pressure in the gas turbine. The low pressure of the working medium determines the small thickness of the walls of the housings and the ease of their heating. This is what makes the gas turbine very maneuverable, i.e. capable of rapid starts and stops. If it takes from 1 hour to several hours to start a steam turbine, depending on its initial temperature state, then a gas turbine unit can be put into operation in 10-15 minutes.

When compressed in a compressor, the air heats up. This heating can be estimated using a simple approximate relationship:

$$T_a/T_b = \pi_к^(0.25)$$

in which T b And T a- absolute air temperatures behind and in front of the compressor. If, for example, T a= 300 K, i.e. ambient air temperature is 27 °C, and p k = 16, then T b= 600 K and, therefore, the air is heated by

$$\Delta t = (600-273)-(300-273) = 300°C.$$

Thus, behind the compressor the air temperature is 300-350 °C. The air between the walls of the flame pipe and the combustion chamber body moves to the burner device, to which fuel gas is supplied. Since the fuel must enter the combustion chamber, where the pressure is 1.3-1.7 MPa, the gas pressure must be high. To be able to regulate its flow into the combustion chamber, gas pressure is required approximately twice as high as the pressure in the chamber. If there is such pressure in the supply gas pipeline, then gas is supplied to the combustion chamber directly from the gas distribution point (GDP). If the gas pressure is insufficient, then a booster gas compressor is installed between the hydraulic fracturing unit and the chamber.

Fuel gas consumption is only approximately 1-1.5% of the air consumption coming from the compressor, so creating a highly economical gas booster compressor presents certain technical difficulties.

Inside the flame pipe 10 high temperature combustion products are formed. After mixing secondary air at the exit from the combustion chamber, it decreases somewhat, but nevertheless reaches 1350-1400 °C in typical modern gas turbines.

From the combustion chamber, hot gases enter the flow part 7 gas turbine. In it, gases expand to almost atmospheric pressure, since the space behind the gas turbine communicates either with a chimney or with a heat exchanger, the hydraulic resistance of which is low.

When gases expand in a gas turbine, power is created on its shaft. This power is partially consumed to drive the air compressor, and its excess is used to drive the rotor 1 electric generator. One of characteristic features The gas turbine system consists of the fact that the compressor requires approximately half the power developed by the gas turbine. For example, in a gas turbine unit with a capacity of 180 MW (this is the useful power) being created in Russia, the compressor power is 196 MW. This is one of fundamental differences GTU from PTU: in the latter, the power used to compress the feed water even to a pressure of 23.5 MPa (240 atm) is only a few percent of the power of the steam turbine. This is due to the fact that water is a poorly compressible liquid, and air requires a lot of energy to compress.

In a first, rather rough approximation, the temperature of the gases behind the turbine can be estimated using a simple relationship similar to:

$$T_c/T_d = \pi_к^(0.25).$$

Therefore, if $\pi_к = 16$, and the temperature in front of the turbine T s= 1400 °C = 1673 K, then the temperature behind it is approximately K:

$$T_d=T_c/\pi_к^(0.25) = 1673/16^(0.25) = 836.$$

Thus, the temperature of the gases behind the gas turbine plant is quite high, and a significant amount of heat obtained from fuel combustion literally goes into the chimney. Therefore, when a gas turbine operates autonomously, its efficiency is low: for typical gas turbines it is 35-36%, i.e. significantly less than the efficiency of the PTU. The matter, however, changes radically when a heat exchanger (network heater or waste heat boiler for a combined cycle) is installed on the “tail” of the gas turbine unit.

A diffuser is installed behind the gas turbine - a smoothly expanding channel, during which the high-speed pressure of gases is partially converted into pressure. This makes it possible to have a pressure behind the gas turbine that is less than atmospheric, which increases the efficiency of 1 kg of gases in the turbine and, therefore, increases its power.

Air compressor device. As already indicated, an air compressor is a turbomachine to the shaft of which power is supplied from a gas turbine; this power is transferred to the air flowing through the compressor flow path, as a result of which the air pressure increases up to the pressure in the combustion chamber.

The figure shows a gas turbine rotor placed in support bearings; The compressor rotor and stator elements are clearly visible in the foreground.

From the mine 4 air enters the channels formed by the rotating blades 2 non-rotating input guide vane (VNA). the main task VNA - impart rotational motion to a flow moving in the axial (or radial-axial) direction. The VNA channels are not fundamentally different from the nozzle channels of a steam turbine: they are confuser (tapered), and the flow in them accelerates, simultaneously acquiring a circumferential velocity component.

In modern gas turbines, the input guide vane is rotary. The need for a rotary VNA is caused by the desire to prevent a decrease in efficiency when the load on the gas turbine plant decreases. The point is that the shafts of the compressor and electric generator have the same rotation frequency, equal to the network frequency. Therefore, if you do not use VNA, then the amount of air supplied by the compressor to the combustion chamber is constant and does not depend on the turbine load. And the power of a gas turbine can only be changed by changing the fuel flow into the combustion chamber. Therefore, with a decrease in fuel consumption and a constant amount of air supplied by the compressor, the temperature of the working gases decreases both in front of the gas turbine and behind it. This leads to a very significant decrease in the efficiency of the gas turbine unit. Rotation of the blades when the load around the axis is reduced 1 by 25 - 30° allows you to narrow the flow sections of the VNA channels and reduce the air flow into the combustion chamber, maintaining a constant ratio between air and fuel flow. Installing an inlet guide vane makes it possible to maintain the temperature of the gases in front of and behind the gas turbine constant in the power range of approximately 100-80%.

The figure shows the drive of the VNA blades. A rotating lever is attached to the axes of each blade 2 which through the lever 4 connected to the turning ring 1 . If it is necessary to change the air flow, the ring 1 rotates using rods and an electric motor with a gearbox; in this case all levers turn simultaneously 2 and accordingly the VNA blades 5 .

The air swirled with the help of a VHA enters the 1st stage of the air compressor, which consists of two gratings: rotating and stationary. Both grilles, unlike turbine grilles, have expanding (diffuser) channels, i.e. area for air passage at the inlet F 1 less than F 2 on output.

When air moves in such a channel, its speed decreases ( w 2 < w 1), and the pressure increases ( R 2 > R 1). Unfortunately, making a diffuser grille economical, i.e. so that the flow rate w 1 would be converted to the maximum extent into pressure, and not into heat, only possible with a small degree of compression R 2 /R 1 (usually 1.2 - 1.3), which leads to a large number of compressor stages (14 - 16 with a compressor compression ratio p k = 13 - 16).

The figure shows the air flow in the compressor stage. Air comes out of the inlet (fixed) rotary nozzle apparatus at a speed c 1 (see the upper triangle of speeds), having the necessary circumferential twist (a 1< 90°). Если расположенная за ВНА вращающаяся (рабочая) решетка имеет скорость u 1, then the relative speed of entry into it w 1 will be equal to the vector difference c 1 and u 1, and this difference will be greater than c 1 i.e. w 1 > c 1 . When moving in the channel, the air speed decreases to the value w 2, and it comes out at an angle b2, determined by the inclination of the profiles. However, due to rotation and the supply of energy to the air from the rotor blades, its speed With 2 in absolute motion will be greater than c 1 . The blades of the fixed grille are installed so that the air entry into the channel is shock-free. Since the channels of this lattice are expanding, the speed in it decreases to the value c"1, and the pressure increases from R 1 to R 2. The grid is designed so that c" 1 = c 1, a a " 1 = a 1. Therefore, in the second stage and subsequent stages, the compression process will proceed in a similar way. Moreover, the height of their gratings will decrease in accordance with the increased air density due to compression.

Sometimes the guide vanes of the first few stages of the compressor are rotatable in the same way as the VNA blades. This makes it possible to expand the power range of the gas turbine unit, at which the temperature of the gases in front of and behind the gas turbine remains unchanged. Accordingly, efficiency increases. The use of several rotary guide vanes allows you to work economically in the range of 100 - 50% power.

The last stage of the compressor is designed in the same way as the previous ones, with the only difference being that the task of the last guide vane is 1 is not only to increase the pressure, but also to ensure an axial outlet of the air flow. Air enters the annular outlet diffuser 23 , where the pressure rises to its maximum value. With this pressure, air enters the combustion zone 9 .

Air is taken from the air compressor housing to cool the gas turbine elements. For this purpose, annular chambers are made in its body, communicating with the space behind the corresponding stage. Air is removed from the chambers using pipelines.

In addition, the compressor has so-called anti-surge valves and bypass pipes 6 , bypassing air from the intermediate stages of the compressor into the outlet diffuser of the gas turbine when it starts and stops. This eliminates unstable operation of the compressor at low air flow rates (this phenomenon is called surging), which is expressed in intense vibration of the entire machine.

The creation of highly efficient air compressors is an extremely complex task, which, unlike turbines, cannot be solved only by calculation and design. Since the compressor power is approximately equal to the power of the gas turbine unit, a deterioration in the efficiency of the compressor by 1% leads to a decrease in the efficiency of the entire gas turbine unit by 2-2.5%. Therefore, creating a good compressor is one of the key issues creation of GTU. Typically, compressors are created by simulation (scaling), using a model compressor created through lengthy experimental development.

The combustion chambers of gas turbine plants are very diverse. Shown above is a gas turbine unit with two remote chambers. The figure shows a 140 MW type 13E gas turbine unit from ABB with one remote combustion chamber, the design of which is similar to that of the chamber shown in the figure. The air from the compressor from the ring diffuser enters the space between the chamber body and the flame tube and is then used for gas combustion and for cooling the flame tube.

The main disadvantage of remote combustion chambers is their large dimensions, which are clearly visible from the figure. A gas turbine is located to the right of the chamber, and a compressor is located to the left. At the top of the housing you can see three holes for placing anti-surge valves and then the VNA drive. Modern gas turbine plants mainly use built-in combustion chambers: annular and tubular-ring.

The figure shows an integrated annular combustion chamber. The annular combustion space is formed by the inner 17 and outdoor 11 flame pipes. The inside of the pipes is lined with special inserts 13 And 16 having a thermal barrier coating on the side facing the flame; on the opposite side, the inserts have fins that improve their cooling by air entering through the annular gaps between the inserts inside the flame tube. Thus, a flame tube temperature of 750-800 °C is achieved in the combustion zone. The front micro-flare burner device of the chamber consists of several hundred burners 10 , to which gas is supplied from four collectors 5 -8 . By turning off the collectors one by one, you can change the power of the gas turbine unit.

The burner structure is shown in the figure. Gas enters from the manifold through drilling in the rod 3 to the inner cavity of the blades 6 swirler. The latter is a hollow radial straight blades that force the air coming from the combustion chamber to twist and rotate around the axis of the rod. This rotating air vortex receives natural gas from the internal cavity of the swirler blades 6 through small holes 7 . In this case, a homogeneous fuel-air mixture is formed, emerging in the form of a swirling jet from the zone 5 . An annular rotating vortex ensures stable gas combustion.

The figure shows the tubular-ring combustion chamber of GTE-180. Into the annular space 24 between the outlet of the air compressor and the inlet of the gas turbine using perforated cones 3 place 12 flame tubes 10 . The flame tube contains numerous holes with a diameter of 1 mm, located in annular rows with a distance of 6 mm between them; the distance between rows of holes is 23 mm. “Cold” air enters from the outside through these holes, providing convective film cooling and a flame tube temperature of no higher than 850 °C. A thermal barrier coating 0.4 mm thick is applied to the inner surface of the flame tube.

On the front plate 8 flame tube, a burner device is installed, consisting of a central pilot burner 6 igniting fuel at start-up using a spark plug 5 , and five main modules, one of which is shown in the figure. The module allows you to burn gas and diesel fuel. Gas through the fitting 1 after the filter 6 enters the annular fuel gas manifold 5 , and from it into cavities containing small holes (diameter 0.7 mm, pitch 8 mm). Through these holes, gas enters the annular space. Six tangential grooves are made in the walls of the module 9 , through which the main amount of air supplied for combustion from the air compressor enters. In the tangential grooves, the air swirls and, thus, inside the cavity 8 a rotating vortex is formed, moving towards the exit of the burner device. To the periphery of the vortex through the holes 3 gas enters, mixes with air, and the resulting homogeneous mixture leaves the burner, where it ignites and burns. Combustion products enter the nozzle apparatus of the 1st stage of the gas turbine.

The gas turbine is the most complex element of a gas turbine unit, which is primarily due to the very high temperature working gases flowing through its flow part: the gas temperature in front of the turbine of 1350 °C is currently considered “standard”, and leading companies, primarily General Electric, are working to master the initial temperature of 1500 °C. Let us recall that the “standard” initial temperature for steam turbines is 540 °C, and in the future - a temperature of 600-620 °C.

The desire to increase the initial temperature is associated, first of all, with the gain in efficiency that it gives. This is clearly seen from the figure summarizing the achieved level of gas turbine construction: increasing the initial temperature from 1100 to 1450 °C results in an increase in absolute efficiency from 32 to 40%, i.e. leads to fuel savings of 25%. Of course, part of this saving is associated not only with an increase in temperature, but also with the improvement of other elements of the gas turbine plant, and the determining factor is still the initial temperature.

To ensure long-term operation of a gas turbine, a combination of two means is used. The first remedy is the use of heat-resistant materials for the most loaded parts that can resist high mechanical loads and temperatures (primarily for nozzles and working blades). If steels (i.e., iron-based alloys) with a chromium content of 12-13% are used for blades of steam turbines and some other elements, then for blades gas turbines They use nickel-based alloys (nimonics), which are capable of withstanding temperatures of 800-850 °C under actual mechanical loads and the required service life. Therefore, together with the first, a second means is used - cooling the hottest parts.

To cool most modern gas turbines, air is taken from various stages of the air compressor. Gas turbines are already operating in which water vapor is used for cooling, which is a better cooling agent than air. The cooling air, after heating in the cooled part, is discharged into the flow path of the gas turbine. This cooling system is called open. There are closed cooling systems in which the coolant heated in the part is sent to a refrigerator and then returned again to cool the part. Such a system is not only very complex, but also requires the recovery of heat collected in the refrigerator.

The cooling system of a gas turbine is the most complex system in a gas turbine plant, which determines its service life. It provides not only the maintenance permissible level working and nozzle blades, but also housing elements, disks carrying working blades, locking bearing seals where oil circulates, etc. This system is extremely branched and is organized so that each cooled element receives cooling air of the parameters and in the quantity necessary to maintain its optimal temperature. Excessive cooling of parts is just as harmful as insufficient cooling, since it leads to increased costs of cooling air, the compression of which in the compressor requires turbine power. In addition, increased air flow rates for cooling lead to a decrease in the temperature of gases behind the turbine, which very significantly affects the operation of equipment installed behind the gas turbine unit (for example, a steam turbine unit operating as part of a steam turbine unit). Finally, the cooling system must provide not only required level temperatures of parts, but also the uniformity of their heating, eliminating the occurrence of dangerous temperature stresses, the cyclic action of which leads to the appearance of cracks.

The figure shows an example of the cooling circuit of a typical gas turbine. The values ​​of gas temperatures are shown in rectangular frames. In front of the 1st stage nozzle apparatus 1 it reaches 1350 °C. Behind him, i.e. in front of the 1st stage working grid it is 1130 °C. Even before the working blade of the last stage it is at the level of 600 °C. Gases of this temperature wash the nozzle and working blades, and if they were not cooled, their temperature would be equal to the temperature of the gases and their service life would be limited to several hours.

To cool the elements of a gas turbine, air is used, taken from the compressor at that stage where its pressure is slightly higher than the pressure of the working gases in the zone of the gas turbine into which air is supplied. For example, to cool the nozzle blades of the 1st stage, cooling air in the amount of 4.5% of the air flow at the compressor inlet is taken from the compressor outlet diffuser, and to cool the nozzle blades of the last stage and the adjacent section of the housing - from the 5th stage of the compressor. Sometimes, to cool the hottest elements of a gas turbine, air taken from the compressor outlet diffuser is first sent to an air cooler, where it is cooled (usually with water) to 180-200 ° C and then sent for cooling. In this case, less air is required for cooling, but at the same time costs arise for the air cooler, the gas turbine becomes more complicated, and part of the heat removed by the cooling water is lost.

A gas turbine usually has 3-4 stages, i.e. There are 6-8 rows of gratings, and most often the blades of all rows are cooled, except for the working blades of the last stage. Air for cooling the nozzle blades is brought in through their ends and discharged through numerous (600-700 holes with a diameter of 0.5-0.6 mm) openings located in the corresponding zones of the profile. Cooling air is supplied to the rotor blades through holes made in the ends of the shanks.

In order to understand how cooled blades are designed, it is necessary to at least in general consider the technology of their manufacture. Due to the exceptional difficulty of machining nickel alloys, precision investment casting is mainly used to produce blades. To implement it, first, casting rods are made from ceramic-based materials using a special molding and heat treatment technology. The casting core is an exact copy of the cavity inside the future blade, into which cooling air will flow and flow in the required direction. The casting core is placed in a mold, the internal cavity of which completely corresponds to the blade that needs to be obtained. The resulting free space between the rod and the wall of the mold is filled with a heated low-melting mass (for example, plastic), which hardens. The rod together with the solidifying mass enveloping it, repeating external form blades, is a lost wax model. It is placed in a casting mold, to which the nimonic melt is fed. The latter melts the plastic, takes its place and as a result a cast blade appears with an internal cavity filled with a rod. The rod is removed by etching with special chemical solutions. The resulting nozzle blades require virtually no additional mechanical processing (except for the manufacture of numerous holes for the exit of cooling air). Cast working blades require processing of the shank using a special abrasive tool.

The technology described briefly is borrowed from aviation technology, where the temperatures achieved are much higher than in stationary steam turbines. The difficulty in mastering these technologies is associated with the much larger sizes of blades for stationary gas turbine plants, which grow in proportion to the gas flow rate, i.e. GTU power.

The use of so-called monocrystalline blades, which are made from a single crystal, seems very promising. This is due to the fact that the presence of grain boundaries during prolonged exposure to high temperatures leads to a deterioration in the properties of the metal.

The gas turbine rotor is a unique prefabricated structure. Before assembly, individual discs 5 compressor and disk 7 gas turbine are bladed and balanced, end parts are manufactured 1 And 8 , spacer part 11 and central tie bolt 6 . Each of the disks has two annular collars on which hirths are made (named after the inventor - Hirth), - strictly radial teeth of a triangular profile. Adjacent pieces have exactly the same collars with exactly the same hilts. With good manufacturing quality of the Hirth connection, absolute alignment of adjacent disks is ensured (this ensures the radius of the Hirths) and repeatability of the assembly after disassembling the rotor.

The rotor is assembled on a special stand, which is an elevator with a ring platform for installation personnel, inside which the assembly is carried out. First, the end part of the rotor is assembled on the thread 1 and tie rod 6 . The rod is placed vertically inside the ring platform and the disk of the 1st stage of the compressor is lowered onto it using a crane. Centering of the disk and the end part is carried out by hirths. Moving upward on a special elevator, the installation staff disc by disc [first the compressor, then the spacer part, and then the turbine and the right end part 8 ] assembles the entire rotor. A nut is screwed onto the right end 9 , and a hydraulic device is installed on the remaining part of the threaded part of the tie rod, squeezing the disks and pulling out the tie rod. After drawing out the rod, the nut 9 screwed in until it stops and the hydraulic device is removed. The stretched rod reliably pulls the disks together and turns the rotor into a single rigid structure. The assembled rotor is removed from the assembly stand, and it is ready for installation in the gas turbine unit.

The main advantage of the gas turbine is its compactness. Indeed, first of all, the gas turbine plant does not have a steam boiler, a structure that reaches a great height and requires a separate room for installation. This circumstance is associated primarily with high pressure in the combustion chamber (1.2-2 MPa); in the boiler, combustion occurs at atmospheric pressure and, accordingly, the volume of hot gases formed is 12-20 times greater. Further, in a gas turbine unit, the process of gas expansion occurs in a gas turbine consisting of only 3-5 stages, while a steam turbine having the same power consists of 3-4 cylinders containing 25-30 stages. Even taking into account both the combustion chamber and the air compressor, a gas turbine unit with a power of 150 MW has a length of 8-12 m, and the length of a steam turbine of the same power with a three-cylinder design is 1.5 times longer. At the same time, for a steam turbine, in addition to the boiler, it is necessary to provide for the installation of a condenser with circulation and condensate pumps, a regeneration system of 7-9 heaters, feed turbopumps (from one to three), and a deaerator. As a result, the gas turbine unit can be installed on a concrete base at the zero level of the turbine room, and the steam turbine unit requires a frame foundation with a height of 9-16 m with the placement of the steam turbine on the upper foundation slab and auxiliary equipment in the condensing room.

The compactness of the gas turbine allows it to be assembled at a turbine plant and delivered to the turbine room by rail or road for installation on a simple foundation. Thus, in particular, gas turbine units with built-in combustion chambers are transported. When transporting gas turbine units with remote chambers, the latter are transported separately, but are easily and quickly connected to the compressor - gas turbine module using flanges. A steam turbine is supplied with numerous units and parts; installation of both itself and numerous auxiliary equipment and connections between them takes several times longer than a gas turbine unit.

The gas turbine unit does not require cooling water. As a result, the gas turbine unit does not have a condenser and a technical water supply system with a pumping unit and a cooling tower (if recycling water supply). As a result, all this leads to the fact that the cost of 1 kW of installed capacity of a gas turbine power plant is significantly less. At the same time, the cost of the gas turbine itself (compressor + combustion chamber + gas turbine), due to its complexity, turns out to be 3-4 times more than the cost of a steam turbine of the same power.

An important advantage of a gas turbine is its high maneuverability, determined by a low pressure level (compared to the pressure in a steam turbine) and, therefore, easy heating and cooling without the occurrence of dangerous temperature stresses and deformations.

However, gas turbine plants also have significant disadvantages, of which, first of all, it is necessary to note their lower efficiency than that of a steam power plant. The average efficiency of fairly good gas turbine units is 37-38%, and that of steam turbine power units is 42-43%. The ceiling for powerful power gas turbines, as it is currently seen, is an efficiency of 41-42% (and maybe higher, taking into account the large reserves for increasing the initial temperature). The lower efficiency of gas turbines is associated with the high temperature of the exhaust gases.

Another disadvantage of gas turbine plants is the impossibility of using low-grade fuels in them, at least at the present time. It can only work well on gas or good liquid fuel, such as diesel. Steam power units can operate on any fuel, including the lowest quality.

The low initial cost of thermal power plants with gas turbines and at the same time the relatively low efficiency and high cost of the fuel used and maneuverability determine the main area of ​​​​individual use of gas turbines: in power systems they should be used as peak or reserve power sources operating several hours a day.

At the same time, the situation changes radically when the heat from the exhaust gases of gas turbine plants is used in heating plants or in a combined (steam-gas) cycle.

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

Important factors in choosing power units are ease of operation, level of maintenance and repair, as well as the location where power unit repairs are performed. These issues are primarily related to the costs and problems that the owner of an autonomous power plant may subsequently have.

In this article, the author does not have a selfish goal to prioritize in favor of piston or turbine technologies. It is more correct and optimal to select the types of power plants of power plants directly to the project, based on the individual conditions and technical specifications of the customer.

When choosing power equipment for the construction of an autonomous gas CHP plant, 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 that can be viewed and taken on a tour. One should also take into account such a factor as the weakness and underdevelopment of the generation equipment market in Russia, the real sales volumes of 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 piston engines vs gas turbine engines - operating costs

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

The cost of overhauling a gas piston engine can be 30–350% of the initial cost of the power unit itself, and not the entire power plant - during overhaul the piston group is replaced. Repair of gas piston units can be carried out on site without complex 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 approximately the same. Real, honest prices for gas turbine and piston units themselves of comparable power and quality are also similar.

Due to its complexity, major repairs of a gas turbine unit are not carried out on site. The supplier must take away the used unit and bring a replacement gas turbine unit. The old unit can only be restored under factory conditions.

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

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

Today, modern autonomous power plants use turbines of industrial design, 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, fuel consumption increases by 40%. The maximum load of a gas turbine unit, 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 units at low loads are resolved positively at the design stage. Design must be of high quality.

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

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

An enterprise connected to the network can install only one installation and use its own electricity at cost, and during maintenance, be powered from the general electrical network, paying according to the meter. This is cheaper than “+1”, but, unfortunately, is not always feasible. This is usually due to the lack of an electrical network at all, or to the incredible high cost technical specifications for the connection itself.

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

On powerful gas piston units, the oil does not need to be changed. With constant work, it is simply produced without having time to age. Oil in such installations is constantly topped up. Such operating modes are provided for by the 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. Burnout is always higher when the load decreases. As a rule, the gas piston engine kit includes a special reservoir for continuous oil addition, and a mini-laboratory for checking its quality and determining the replacement period.

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

Since engine oil does burn out, piston units have a slightly higher level of harmful emissions into the atmosphere than gas turbine units. But since gas burns completely and is one of the cleanest types of fuel, talking about serious air pollution is just “dulling the swords.” A couple of old Hungarian Ikarus buses cause much more serious harm to the environment. To comply with environmental requirements, when using piston machines, it is necessary to build higher chimneys, taking into account the existing level of maximum permissible concentrations in the environment.

Used oil from gas piston plants cannot simply be poured onto the ground - it requires disposal - this is an “expense” for the owners of the power plant. But you can make money from this - used motor oil is bought by specialized organizations.

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

The same is true at piston power plants: - you don’t need to be afraid of engine oil consumption, it won’t ruin you, during 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 units, oil is used only in the gearbox. Its volume can be considered insignificant. Replacement gear oil in a gas turbine unit it is produced on average once every 3-5 years, and refilling is not required.

To carry out full service, a powerful gas piston installation must include a beam crane. Using a crane beam, heavy parts of piston engines are removed. The use of a beam crane requires high ceilings for the machine rooms of a reciprocating power plant. To repair gas piston units of low and medium power, you can get by with simpler lifting mechanisms.

When delivered, gas piston power plants can be equipped with various repair tools and accessories. Its presence implies that even all critical operations can be carried out by qualified personnel on site. Virtually all repair work on gas turbines can be carried out either at the manufacturer's factory or with the direct assistance of factory specialists.

Spark plugs need to be replaced once every 3-4 months. Replacing spark plugs is only 1-2 (!) kopecks in the cost of 1 kW/h of own electricity.

Piston units, unlike gas turbine units, are liquid cooled; therefore, the personnel of an autonomous power plant must constantly monitor the level of coolant and periodically replace it, and if it is water, then it must be chemically prepared.

The above-mentioned operating features of piston units are absent in gas turbine units. Gas turbine installations do not use consumables and components such as:

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

But gas turbines cannot be repaired on site, and the much higher gas consumption cannot be compared with the costs of operation and consumables for piston units.

What to choose? Gas piston or gas turbine units?

How do the power of power plant power units relate to the ambient temperature?

With a significant increase in ambient temperature, the power of the gas turbine unit decreases. But as the temperature decreases, the electrical power of the gas turbine unit, on the contrary, increases. Electrical power parameters, according to existing ones ISO standards, measured at t +15 °C.

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

The high temperature at the outlet of gas turbine units allows the use of a steam turbine as part of the power plant. This equipment is in demand if the consumer needs to obtain the maximum amount of electrical energy with the same volume of gas fuel consumed, and thus achieve 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 that have steam turbines in their structure, as a rule, are designed for quite high power - from 50 MW and above.

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

The efficiency of a power plant is more than relevant - after all, it affects fuel consumption. The average specific consumption of gas fuel per 1 kW/hour generated is significantly lower 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 that of gas turbines is 23–33% (in the steam-gas cycle, the turbine is capable of achieving an efficiency of up to 59%).

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

If you need to manufacture a locomotive, an airplane or a marine vessel, then the efficiency factor of the power plant can be considered one of the determining indicators. The heat that is generated 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 complete use of combustible fuel - the fuel utilization factor (FUI).

When burned, the fuel does the main work - it rotates the power plant generator. All the remaining energy from fuel combustion is heat, which can and should be used. In this case, the so-called “overall efficiency”, or rather the fuel utilization factor (FUI), of the power plant will be about 80-90%.

If the consumer expects to use thermal energy autonomous power plant in full, which is usually unlikely, then the efficiency factor (efficiency) of the autonomous power plant does not have practical significance.

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

In addition, turbines require high gas inlet pressure, and for this they necessarily install compressors (piston ones) and they also increase fuel consumption.
A comparison of gas turbine units 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 thermal needs with a power of over 30-40 MW.

From the above it follows that the electrical efficiency of power units of 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 from gas piston installations. Gas is the main expense item when operating an autonomous power plant!

Gas piston installations versus gas turbine engines - gas inlet pressure

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

For all types of modern power units of power plants, the gas supply pressure has no practical significance, since the gas turbine unit always includes a gas compressor, which is included in the cost of the energy complex.

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

However, we should not forget that The booster compressor also requires a lot of energy, Supplies and services. Paradoxically, piston compressors are often used for powerful turbines.

Gas piston engines versus gas turbine units - dual fuel units

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

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

• in the absence of natural gas, the installation automatically switches to operating on diesel fuel;
• During transient processes, the installation automatically switches to operating on diesel fuel.

When reaching the operating mode, the reverse process of switching to operation on natural gas and diesel fuel is carried out;
We should not forget the fact that the first turbines were initially designed to run on liquid fuel - kerosene.

Dual-fuel installations still have 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

What can be the number of starts of gas piston units?

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 supply for their own needs, can lead to wear of the most loaded components (turbocharger bearings, valves, etc.).

Due to sudden changes in thermal stresses that arise in the most critical components and parts of the hot section of a gas turbine unit during rapid 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 units - resource until overhaul

What can be the service life of the installation before major repairs?

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

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

What capital investments will be required for the construction of a power plant? What is the cost of building an autonomous turnkey energy complex?

As calculations show, capital investment (dollar/kW) in the construction of a thermal power plant with gas piston engines is approximately equal to that of gas turbine units. 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 units, completely turnkey, will cost $15.3 million.

Gas piston engines versus gas turbine units - ecology

How are environmental requirements met?

It should be noted that gas piston units are inferior to gas turbine units in terms of NOx emissions. Since engine oil burns out, piston units have a slightly higher level of harmful emissions into the atmosphere than gas turbine units.

But this is not critical: the SES requests the background level according to the maximum permissible concentration at the location of the mini-CHP. After this, a dispersion calculation is made so that the “addition” of harmful substances from the mini-CHP added to the background does not lead to exceeding the maximum permissible concentration. Through several iterations, the minimum height is selected chimney, in which the requirements of SanPiN are met. The addition from a 16 MW station in terms of NOx emissions is not so significant: with a chimney height of 30 m - 0.2 MAC, at 50 m - 0.1 MAC.

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 significance.

Piston units experience vibration and low-frequency noise during operation. Bringing noise to standard values ​​is possible, you just need appropriate engineering solutions. In addition to calculating dispersion when developing a section 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 certain frequency spectrum. Gas turbine installations have not escaped this crisis.

Gas piston installations versus gas turbine engines - conclusions

Under linear loads and compliance with the N+1 rule, the use of gas piston engines as the main source of power supply is possible. Such a power plant requires backup units and storage tanks for the second type of fuel - diesel.

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

In the case of using gas piston units, the consumer can completely avoid external power supply, but only with a thoughtful and balanced approach.

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

Some alternative to piston units is gas microturbines. True, prices for microturbines are very steep and amount to ~ $2500–4000 per 1 kW of installed power!

A comparison of gas turbine units 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 generation plants, 200,000 operating hours is not a critical value and, subject to the scheduled maintenance schedule and phased replacement of turbine parts subject to wear: bearings, injectors, various auxiliary equipment (pumps, fans), further operation of the gas turbine plant remains economically feasible. High-quality gas piston units today also successfully overcome 200,000 operating hours.

This is confirmed by modern practice in the operation of gas turbine/gas piston plants throughout the world.

When choosing power units of an autonomous power plant, specialist consultation is necessary!

Expert advice and supervision are also necessary during 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, unbiasedly and objectively determine the choice of main and auxiliary equipment to select the optimal configuration - the configuration of your future power plant.

Qualified engineering allows you to save significant money for the customer, which is 10–40% of the total costs. Engineering from professionals in the electrical power industry allows you to avoid costly mistakes in design and in choosing equipment suppliers.

In autonomous generation - small-scale energy, considerable attention has recently been paid to gas turbines different power. Power plants at the base gas turbines are used as the main or backup source of electricity and thermal energy for industrial or domestic purposes. Gas turbines as part of power plants are designed for operation in any climatic conditions of Russia. Areas of use gas turbines practically unlimited: oil and gas industry, industrial enterprises, housing and communal services structures.

Positive factor of use gas turbines in the housing and communal services sector is that the content of harmful emissions in the exhaust gases NO x and CO is at the level of 25 and 150 ppm, respectively (for reciprocating units these values ​​are much higher), which makes it possible to install a power plant next to residential buildings. Usage gas turbines as power units of power plants avoids the construction of high chimneys.

Depending on your needs gas turbines is equipped with steam or hot water waste heat boilers, which allows you to receive either steam (low, medium, high pressure) from the power plant for technological needs, or hot water(DHW) with standard temperature values. You can get steam and hot water at the same time. The power of thermal energy produced by a power plant based on gas turbines is usually twice that of electricity.

At the power plant with gas turbines in this configuration, the fuel efficiency increases to 90%. High efficiency use gas turbines as power units is ensured during long-term operation at maximum electrical load. At high enough power gas turbines There is a possibility of combined use of steam turbines. This measure can significantly improve the efficiency of the power plant, increasing the electrical efficiency to 53%.

How much does a power plant based on gas turbines cost? What is its full price? What is included in the turnkey price?

An autonomous thermal power plant based on gas turbines has a lot of additional expensive, but often simple necessary equipment(real life example – completed project). Using first-class equipment, the cost of a turnkey power plant of this level does not exceed 45,000 - 55,000 rubles per 1 kW of installed electrical power. The final price of a power plant based on gas turbines depends on the specific tasks and needs of the consumer. The price includes design, construction and commissioning work. Gas turbines themselves, as power units, without additional equipment, depending on the manufacturing company and power, cost from 400 to 800 dollars per 1 kW.

To obtain information about the cost of building a power plant or thermal power plant in your specific case, you must send a completed questionnaire to our company. After this, after 2–3 days, the customer-client receives a preliminary technical and commercial proposal - TCP (brief example). Based on the TCP, the customer makes the final decision on the construction of a power plant based on gas turbines. As a rule, before making a decision, the client visits an existing facility to see a modern power plant with his own eyes and “touch everything with his hands.” The customer receives answers to his questions directly at the site.

The construction of power plants based on gas turbines is often based on the concept of block-modular construction. Block-modular design ensures a high level of factory readiness of gas turbine power plants and reduces the construction time of energy facilities.

Gas turbines - a little arithmetic on the cost of energy produced

To produce 1 kW of electricity, gas turbines consume only 0.29–0.37 m³/hour of gas fuel. When burning one cubic meter of gas, gas turbines generate 3 kW of electricity and 4–6 kW of thermal energy. With the price (average) for natural gas in 2011 3 rubles. per 1 m³, the cost of 1 kW of electricity obtained from a gas turbine is approximately 1 ruble. In addition to this, the consumer receives 1.5–2 kW of free thermal energy!

With an autonomous power supply from a power plant based on gas turbines, the cost of electricity and heat produced is 3–4 times lower than the current tariffs in the country, and this does not take into account high cost connections to state power grids (60,000 rubles per 1 kW in the Moscow region, 2011).

Construction of autonomous power plants based on gas turbines allows for significant savings Money By eliminating the costs of construction and operation of expensive power transmission lines (PTL), power plants based on gas turbines can significantly increase the reliability of electrical and heat supplies for both individual enterprises or organizations, and regions as a whole.
The degree of automation of a power plant based on gas turbines makes it possible to eliminate a large number of maintenance personnel. During operation gas power plant Its operation is ensured by only three people: an operator, an electrician on duty, and a mechanic on duty. In the event of emergency situations, reliable protection systems are provided to ensure the safety of personnel and the safety of gas turbine systems and assemblies.

Atmospheric air through an air intake equipped with a filter system (not shown in the diagram) is supplied to the input of a multi-stage axial compressor. The compressor compresses atmospheric air and supplies it at high pressure to the combustion chamber. At the same time, a certain amount of gas fuel is supplied to the combustion chamber of the turbine through nozzles. Fuel and air mix and ignite. The fuel-air mixture burns, releasing a large amount of energy. The energy of gaseous combustion products is converted into mechanical work due to the rotation of turbine blades by jets of hot gas. Part of the energy received is spent on air compression in the turbine compressor. The rest of the work is transferred to the electric generator through the drive axis. This work is the useful work of a gas turbine. Combustion products, which have a temperature of about 500-550 °C, are discharged through the exhaust tract and turbine diffuser, and can be further used, for example, in a heat exchanger, to obtain thermal energy.

Gas turbines, as engines, have the highest power density among internal combustion engines, up to 6 kW/kg.

The following gas turbine fuels can be used: kerosene, diesel fuel, gas.

One of the advantages of modern gas turbines is long life cycle- motor life (total up to 200,000 hours, before major repairs 25,000–60,000 hours).

Modern gas turbines are highly reliable. There is evidence of continuous operation of some units for several years.

Many gas turbine suppliers produce major renovation equipment on site, replacing individual components without transportation to the manufacturer, which significantly reduces time costs.

The possibility of long-term operation in any power range from 0 to 100%, the absence of water cooling, operation on two types of fuel - all this makes gas turbines popular power units for modern autonomous power plants.

The most effective use of gas turbines is at average power plant capacities, and at capacities above 30 MW, the choice is obvious.

“Turbocharging”, “turbojet”, “turboprop” - these terms have firmly entered the vocabulary of 20th century engineers involved in design and maintenance Vehicle and stationary electrical installations. They are even used in related fields and advertising, when they want to give the product name some hint of special power and efficiency. The gas turbine is most often used in aviation, rockets, ships and power plants. How is it structured? Does it run on natural gas (as you might think from the name), and what types of gas are they? How does a turbine differ from other types of internal combustion engine? What are its advantages and disadvantages? An attempt to answer these questions as fully as possible is made in this article.

Russian engineering leader UEC

Russia, unlike many other independent states formed after the collapse of the USSR, managed to largely preserve the machine-building industry. In particular, the Saturn company is engaged in the production of special-purpose power plants. The company's gas turbines are used in shipbuilding, the raw materials industry and the energy sector. The products are high-tech; they require a special approach during installation, debugging and operation, as well as special knowledge and expensive equipment for routine maintenance. All these services are available to customers of the company "UEC - Gas Turbines", as it is called today. There are not so many such enterprises in the world, although the principle of the main product is simple at first glance. The accumulated experience is of great importance, allowing us to take into account many technological subtleties, without which it is impossible to achieve durable and reliable operation of the unit. Here is just part of the UEC product range: gas turbines, power plants, gas pumping units. Among the customers are Rosatom, Gazprom and other “whales” chemical industry and energy.

Manufacturing 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 installation diagrams matter in each individual case.

And it all started so simply...

Searches and pairs

Humanity carried out the first experiments in converting the translational energy of a flow into rotational force in ancient times, using an ordinary water wheel. Everything is extremely simple, liquid flows from top to bottom, and blades are placed in its flow. The wheel, equipped with them around the perimeter, spins. A windmill works the same way. Then came the age of steam, and the rotation of the wheel accelerated. By the way, the so-called “aeolipil”, invented by the ancient Greek Heron about 130 years before the birth of Christ, was a steam engine operating on precisely this principle. In essence, it was the first gas turbine known to historical science (after all, steam is a gaseous state of aggregation water). Today it is still customary to separate these two concepts. At that time in Alexandria they reacted to Heron’s invention without much enthusiasm, although with curiosity. Turbine-type industrial equipment appeared only at the end of the 19th century, after the creation by the Swede Gustaf Laval of the world's first active power unit equipped with a nozzle. Engineer Parsons worked in approximately the same direction, equipping his machine with several functionally related stages.

Birth of gas turbines

A century earlier, a certain John Barber came up with a brilliant idea. Why do you need to heat the steam first? Isn’t it easier to directly use the exhaust gas generated during the combustion of fuel, and thereby eliminate unnecessary mediation in the energy conversion process? This is how the first real gas turbine turned out. The 1791 patent outlines the basic idea for use in a horseless carriage, but its elements are today used in modern rocket, aircraft tank and automobile engines. The process of jet engine construction was started in 1930 by Frank Whittle. He came up with the idea of ​​using a turbine to propel an airplane. Subsequently, it was developed in numerous turboprop and turbojet projects.

Nikola Tesla gas turbine

The famous scientist-inventor always approached the issues he studied in a non-standard way. It seemed obvious to everyone that wheels with paddles or paddles “catch” the movement of the medium better than flat objects. Tesla, in his characteristic manner, proved that if you assemble a rotor system from disks arranged sequentially on the axis, then due to the gas flow picking up the boundary layers, it will rotate no worse, and in some cases even better, than a multi-bladed propeller. True, the direction of the moving medium must be tangential, which is not always possible or desirable in modern units, but the design is significantly simplified - it does not require blades at all. A gas turbine according to Tesla’s scheme is not yet being built, but perhaps the idea is just waiting for its time.

Schematic diagram

Now about the basic 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 working blades is placed on the shaft, forming a concentric lattice; they are exposed to gas supplied under pressure through special nozzles. The expanded gas then enters the impeller, which is also equipped with blades called workers. Special pipes are used for the intake of the air-fuel mixture and the outlet (exhaust). A compressor is also involved in the overall scheme. It can be made according to different principles, depending on the required operating pressure. To operate it, part of the energy is taken from the axis and used to compress the air. A gas turbine operates through the combustion process of an air-fuel mixture, accompanied by a significant increase in volume. The shaft rotates, its energy can be used usefully. Such a circuit is called single-circuit, but if it is repeated, then it is considered multi-stage.

Advantages of aircraft turbines

Around the mid-fifties, a new generation of aircraft appeared, including passenger aircraft (in the USSR these were Il-18, An-24, An-10, Tu-104, Tu-114, Tu-124, etc.), in designs in which aircraft piston engines were finally and irrevocably replaced by turbine engines. This indicates the greater efficiency of this type of power plant. The characteristics of a gas turbine exceed those of carburetor engines in many respects, in particular in terms of power/weight ratio, which is of paramount importance for aviation, as well as in no less important indicators reliability. Lower fuel consumption, fewer moving parts, better environmental parameters, reduced noise and vibration. Turbines are less critical to fuel quality (which cannot be said about fuel systems), they are easier to maintain, and they do not require as much lubricating oil. In general, at first glance it seems that they are not made of metal, but of solid advantages. Alas, this is not true.

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 modified layout scheme that involves washing the lower part of the tail unit with a jet stream. And the engine housing itself requires special thermal insulation and the use of special refractory materials that can withstand high temperatures.

Cooling gas turbines is a complex technical challenge. It's no joke, they operate in a mode of virtually permanent explosion occurring in the body. The efficiency in some modes is lower than that of carburetor engines; however, when using a dual-circuit circuit, this drawback is eliminated, although the design becomes more complicated, as is the case when “boosting” compressors are included in the circuit. Accelerating the turbines and reaching operating mode takes some time. The more often the unit starts and stops, the faster it wears out.

Correct Application

Well, no system is without its shortcomings. It is important to find a use for each of them in which its advantages will be more clearly demonstrated. For example, tanks such as the American Abrams, whose power plant is based on a gas turbine. It can be filled with anything that burns, from high-octane gasoline to whiskey, and produces great power. The example may not be very successful, since experience in Iraq and Afghanistan has shown the vulnerability of compressor blades to sand. Gas turbines have to be repaired in the USA, at the manufacturing plant. To take the tank there, then back, and the cost of the maintenance itself plus components...

Helicopters, Russian, American and other countries, as well as powerful speedboats, suffer less from blockages. Liquid rockets cannot do without them.

Modern warships and civilian ships also have gas turbine engines. And also energy.

Trigenerator power plants

The problems that aircraft manufacturers faced are not as worrying to those who produce industrial equipment for the production of electricity. In this case, weight is no longer so important, and you can focus on parameters such as efficiency and overall efficiency. Gas turbine generator units have a massive frame, a reliable frame and thicker blades. It is quite possible to utilize the generated heat, using it for a variety of needs - from secondary recycling in the system itself, to heating domestic premises and thermal supply of absorption-type refrigeration units. This approach is called trigenerator, and the efficiency in this mode approaches 90%.

Nuclear power plants

For a gas turbine, it makes no fundamental difference what the source of the heated medium is that gives its energy to its blades. This could be a burnt air-fuel mixture, or simply superheated steam (not necessarily water), the main thing is that it ensures uninterrupted power supply. At its core power plants All nuclear power plants, submarines, aircraft carriers, icebreakers and some military surface ships (missile cruiser Peter the Great, for example) are based on a gas turbine (GTU) rotated by steam. Safety and environmental issues dictate 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; they are produced in small batches or even single copies are made. Most often, units produced in large quantities are used in peaceful sectors of the economy, for example, for pumping hydrocarbon raw materials through pipelines. These are exactly the ones produced by the ODK company under the Saturn brand. Gas turbines of pumping stations fully correspond to their name. They actually pump natural gas, using its energy for their work.