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Next Steam turbines for Power Plants: creation experience and development prospects
Alexander Tsvetkov Power Machines, Machines, Russia Russi a Power-Gen Europe 2005, Milan, 28-30.06.2005
INTRODUCTION
Power generating plants of Russia are mostly provided by the equipment of Russian make. The largest Russian manufacturer of steam turbines is LMZ which occupies one of the leading l eading positions in the world. It contributes 75% of the installed capacity in the states of the former USSR and 9% of the world’s power generation. Several years ago LMZ together with the leading Russian manufacturer of power generators (Electrosila), minor steam turbines (KTZ), turbine blades (ZTL), Central-Research Institute (CKTI) and sales company (Energomachexport) formed united power building
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CONVENTIONAL AND MODERN APPROACHES
Beginning from 1940 up to recent time LMZ turbine design concept is based on the use of a relatively small number of turbine cylinders. HP, IP, and LP cylinders are designed for a certain range of steam flow and parameters in such a way that the required output range and initial steam conditions will be met by combinations of cylinders. For example, 300, 500, and 800 MW turbines presently manufactured by LMZ are based on an LP cylinders with 1200 mm titanium moving blade instead of 960 mm stainless steel blade formerly employed ( Figure 2 ). The major features of LMZ turbines are the following: §
All turbines are tandem-compound tandem-compound and operate at 50 cycles.
§
Governing valves with partial arc admission are used in all turbines up to 800 MW.
§
LPC last stage is equipped with stainless steel and titanium blades, including heat monitoring system (Figure 3 ).
§
Impulse type blades, diaphragm-disk design of steam path, optimum positive value of reaction in root section with increasing level of reaction towards the blade periphery.
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All moving blades have covering shrouds or integrally milled shrouds. In IP and LP cylinders integrally milled shrouds improve steam path efficiency and provide damping by friction
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development of efficient steam turbines for Combined Cycle Units.
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development of turbines for supercritical steam parameters for coal fired TPS.
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development of steam turbines for Nuclear Power Plants of new generation.
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upgrading of old steam turbines
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High reliability and efficiency of modern LMZ turbines is provided by the following factors: §
modern cycle arrangements.
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up-to-date methods of profiles, including three-D mathematic simulation (Figure 10).
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application of reactive type-blading in HP and IP cylinders.
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application of the developed shrouding and sealings.
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aerodynamic testing of the steam path components.
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LPC testing on a unique full-scale investigation facility at LMZ factory providing fundamental wide-range research work.
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reasonable choice of the materials and manufacture technologies.
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quality inspection at all stages of manufacture.
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final bench tests. STEAM TURBINES FOR COMBINED CYCLE UNITS
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grade – 25X1M1? ? . LPC is welded, made of carbon steel. LP rotor is solid-forged made of steel 26XM3M2? ? . Spray cooling system is provided for LPC at low flow modes. TURBINES FOR SUPERCRITICAL STEAM PARAMETERS FOR COAL FIRED TPS
The main parameters and longitudinal section of steam turbine K-350-290 (TPP “Novocherkaskaya” in Russia) for supercritical steam conditions are shown in Figure 12. The turbine design is single-shaft with HP, IP and LP cylinders. The reheat line is placed between HPC and IPC. HPC has a throttle-type steam distribution, with two casings – inner and outer and has 14 active stages. Steam flow turn to 180 o is provided for inner casing and steam admission area cooling. IPC is single flow with 15 active stages. LPC is double flow with 4 stages in each flow with the last stage blades of 1200 mm effective length from titanium alloy. All LPC stationary blades are tangentially assembled. Rotors of all cylinders are solid-forged. Spherical, self-adjusted thrust-journal bearing is located between HPC and IPC. Applied materials for the turbine components for supercritical conditions are shown in Figure 13. Steel grade 15X11M? ? ? is applied for high-temperature cast casing components. For
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application of solid-forged rotors with semi-couplings. LP solid-forged rotors with speed of 3000 r/m without central opening, made of ingot blanks of 235 tons which finally have pure mass of 75 tons. Such rotors are a novelty in the world power industry which makes it possible to increase operational reliability in comparison with those made by welding as well as reduce man hour while manufacturing.
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application of moving blades in all stages with integrally milled shrouds.
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damping of moving blades achieved by the created friction in the shrouds makes it possible to avoid the necessity of damping wire installation in the turbine flow path. This provides high vibration reliability and blading efficiency.
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installation of stop and governing valves both at HPC and LPC inlets. Availability of both types of valves at LPC inlet provides reliability of turbine protection from speed-up which is very important taking into account considerable amounts of steam and moisture in separatorreheater.
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due to the fact that HPC casing and components are made of stainless steel the problem of inter-row gap erosion requiring much maintenance and expenses becomes solved .
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HPC shrouds of blades are designed to have an inclined inner surface that stabilizes film moisture flow and helps to remove it out of the turbine with the extracted steam.
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Hours in operation, thousands of hours Park service life (determined by LMZ), thousands of hours
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218
233
205
211
206
210
220
Most components located in HPC and operated under creep conditions at temperature more than 450 oC and at pressure 90 bar take the most wear redoubled by the phenomenon known as metal fatigue (rotor, inner cylinder, etc). As a result they appear to be the first to expire their actual service life. In this case upgrading is made by means of HPC components replacement saving HPC outer casing (Figure 18). This upgrading is aimed at considerable reliability and efficiency improvement of 300 MW power units and increase of their rated power up to 320 MW. HPC design is based on modern methods of steam path calculation in 3-D model and accumulated experience as a result of actual research tests for 300 MW turbine cylinders at the power plants. The main features of new HPC design are as follows: §
reactive type blading is used instead of impulse one.
§
stationary blades are tangentially assembled and special designing of the root area leakages optimal directed.
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Owing to the fact that the turbine K-300-240 is applied with boiler units, running both at constant initial pressure and at sliding one, the new HPC design retains nozzle steam distribution within the governing stage. Materials applied for upgraded HPC components are shown in Figure 20. SUMMARY
Design features and some aspects of efficiency improvement of LMZ turbines are presented. The progress of turbine development in comparing with preceding design is given. LMZ design philosophy and proven engineering approaches are able to provide any expected configuration and performance characteristics of the power plant, operational profile and purchase contract stipulations.
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Figure 1. Main Technical Characteristics of Steam Turbines Produced by LMZ Figure 2. New Design Arrangement of 350-850 MW Steam Turbines Based on LPC with 1200 mm Titanium Moving Blade Figure 3. Range of LPC Last Stage Moving Blade Figure 4. Different Types of Shrouds Figure 5. LPC Control Grid Diaphragm Before and After Modification Figure 6. LPC Last Stage with Interchannel Moisture Separation and Film Moisture Removal Figure 7. TPP equipment in Russia classified in accordance with the operating period (%) Figure 8. Fuel consumption for TPS in Russia (%) Figure 9. Exhaustion of park service life for TPS rated (GW) Figure 10. 3-D Stage Calculation Results Figure 11. Steam Turbine of 80 MW for CCP “Banhida” in Hangary Figure 12. Steam Turbine of 350 MW on Supercriticl Conditions for Novocherkasskaya TPP in Russia Figure 13. Applied Materials for Turbine Components for Supercritical Conditions
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Turbine
R-50-130(90) K-55-90 T-60-112 ? ? -65-90/13 PT-65-130/13 ? T-80-130/13 ? -110-90
Nominal (maximal) electric power value, MW 52,7(60) 55(57) 55(75) 64(75) 65(75) 80(100) 110(115)
Maximal steam disposal on turbine, t/h 470 217 270 398 396 470 420
II T-180/210-130-l ? -180/215-130-2 ? -180/215-130*) ? -190/220-170*) ? -200-130-7 ? -210-130-8 ? -200-130-9 ? -215-130-1(2) ? -225-130 ? -200-181 ? -300-170 ? -330-170*) ? 450 130
180(210) 180(215) 185(215) 190(220) 200(200) 210(210) 200 (200) 215(220) 225(225) 200(220) 310(310) 330(330) 450
I
III ? 300-240-2T
Unsaturated steam
Intermediate superheat
130 90 112 90 130 130 90
555 535 530 535 555 555 535
_ -
-
3 7 6 6 6 6 7
Temperature of feeding water °C 238 226 227 237 237 250 227
670 670 670 670 670 670 670 670 670 655 960 1050 1150
130 130 130 170 130 130 130 130 130 181 170 170 130
540 540 540 540 540 535 540 540 540 535 540 540 540
25.4 25.4 26.2 27.5 24.5 24.6 24.7 24.1 23.6 22.0 39.1 3.0 36.6
540 540 540 540 540 535 540 540 540 535 540 540 54
7 7 7 7 7 7 7 7 7 7 7 7 1
Pressure kg(f)/cm² (abs.)
Temperat. °C
Pressure kg(f)/cm² (abs.)
Temperat. °C
Extraction conditions
Cooling water The number of regenerative bleed-off
power and heat
Discharge, Temperature m3 /h at condencer inlet °C -
Pressure (abs.) kg(f)/cm²
Industrial
Upper
Lower
Heat load Gcal/h
8000 7000 8000 8000 8000 16000
10 5 20 20 20 10
0.4-2.5 0.6-2.5 -
0.3-1. 5 0.7-2.5 0.7-2. 5 0.3-1.0 -
105 68(85) 60(84) 68(100) -
250 250 250 263 248 247 249 245 249 253 256 259 65
22000 22000 22000 22000 VCU 27500 VCU 25000 27500 25000 26000 38000 45000
27 20 27 27 30 12 5 22 25 12
0.6-2.0 0.6-2.0 0.6-2.0 0.6-2.0 5,0
0.5-1. 5 0.5-1. 5 0.5-1. 5 0.5-1. 5 0,9
Pressure Ammount of hg(f)/?m² extracted (abs.) steam t/h 7-21 320(415) 10-16 10-16 10-16 -
155(250) 140(250) 185(300) -
260 260 275 265 100
-
-
310(310)
1000
240
540
40.1
540
8
276
36000
25
-
-
-
-
-
300(314) 500(525) 500(535) 800(850)
975 1715 1650 2650
240 166 240 240
540 530 540 540
37.3 37.3 38.3 34.1
540 535 540 540
8 7 8 8
278 245 276 274
36000 68500 51480 73000
12 24 12 12
-
-
-
-
-
IY ? -1000-60/3000**)
1103
6320
60
x-0,995
5,6
250
8
224
170000
20
-
-
570
-
-
? -1065-60/3000**)
1078
6380
60
x-0.995
6,7
250
6
225
140000
20
-
-
912
-
-
Y ? -35-6***)
35
230/46
6
x-0,995
-
-
-
-
12500
15
-
-
-
-
-
? -150-7,7
170
80+110
75
510
-
-
1
65
27500
15
7,0
0,3
170
-
-
? -150-7,7
160
480+110
78
-
-
3
65
27500
15
6,0
1,5
340
-
-
? -300-240-3 ? -500-160 ? -500-240? -800-240-5
510
NOTES : 1. ? - kondensation; T - with controlled power-and-heat extraction; PI - with controlled industrial and power-ane-heat extraction; R - with back-pressure. 2. Designed for 3000 rpm. 3. In bracket - maximum values. 4 . *) - are being designed at present. 5. **)- for Nuclear PS. 6. ***) - for Geothermal PS.
Figure 1. Main Technical Characteristics of Steam Turbines Produced by LMZ
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30-50 years
5-20 years
30%
35%
20-30 years
35 Figure 7. TPP equipment in Russia classified in accordance with the operating period (%)
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120
115,5
100
85 80
71
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Long-term strength, s 100000 Ref. ? 1
Material
Application
T=575ºC
T=600ºC
?2? ? (25? 1? 1? ? )
HP and IP rotors
100
2
? 11? ? ? ? ?
HP and IP rotors
3
15? 1? 1? (? )
Casings
100
60
4
1? 11? ? ? (? )
Casings
100
70
5
? ? -756(1? 12? 2? ? )
Pipelines
>80
120
Creep limits and long-term stregth for Steel 15? 11? ? ? (? ) (s 0,2=470 MPa) T, ºC
s1/100000
s1000
s10000
s100000
565
-
160
140
120
580
70
210
150
100
600
55
120
90
70
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Reactor rated thermal output, MW
3000
Rated live steam flow, kg/s
1661,1
Rated absolute live steam pressure, MPa
5,88
Rated live steam temperature, ºC
274,3
Rated degree of live steam moisture, %
0,5
Absolute steam pressure at HPC outlet, MPa
0,750
Degree of moisture after separation, %
0,5
Absolute steam pressure after steam reheater, MPa
0,698
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Ref Object ?
Mechanical properties
Elements, percent
Material C
Mo
V
Ti
Nb
11.8 ÷13.5
2.7 0.7 ≤ ≤ 0.025 0.025 ÷3.3 ÷1.2
50 ÷70
≥ 70
2
Inside HP 11.8 06? 12? 3? -? ≤ 0.06 ≤ 0.6 ≤ 0.4 housing ÷13.5
2.7 0.7 ≤ ≤ 0.025 0.025 ÷3.3 ÷1.2
50 ÷70
≥ 70
3
LPC casing
St. 3
≤ 0.05
≤ 0.3 ≤ 0.3
≥ 21
38 ÷ 49
4 HP rotor
30? ? 3? 1? ?
0.17 1.25 0.26 0.47 0.12 ≤ ÷0.4 ÷1.7 ÷0.33 ÷0.73 ÷0.2 0.17 8 5
3.3 ≤ ≤ ≤ 0.2 0.015 0.015 ÷3.8
60 ÷ 72
≥ 75
5 LP rotor
26XH3M2? A
0.24 0.28 ≤ 1.25 0.48 0.1 ÷0.31 ÷0.62 0.15 ÷1.75 ÷0.72 ÷0.2
3.3 ≤ ≤ ≤ 0.015 0.015 ÷3.8 0.25
60 ÷ 77
≥ 72
15? 11? ? -?
0.11 10.0 ≤ 0.7 ≤0.5 ÷0.2 ÷11.5
Outside 1 HP housing
Moving blades 6 (last stage)
Si
Cr
06? 12? 3? -? ≤ 0.06 ≤ 0.6 ≤ 0.4
20? 13-? BT-6
7 Stationary blades
Mn
06? 12? 3?
0.14 0.4 0.12 ≤ 0.3 ÷0.22 ÷0.65 ÷ 0.3
S
0.58 0.23
÷ ÷ 0.82 0.42
0.15 12.0 ≤ 0.6 ≤0.6 ÷0.26 ÷14.0
≤ 0.03
P
≤ 0.04
≤ 0.035
Ni
Cu
KCU KCV σ0.2 σB δ ψ 2 2 kJ/m kJ/m HB 2 2 kgf/mm kgf/mm % % 2 W (kg⋅m/?m ) (kg⋅m/?m2)
≤ 0.6 ≤ 0.3 68 ÷ 80
≤ ≤ ≤ 0.6 0.025 0.03
Titanium, Al5.5-6.7, V 3.5-4.5, ? 0.1, Fe 0.4
≤ 0.06 ≤ 0.6 ≤ 0.4
11.9 ÷13.6
2.7 0.7 ≤ ≤ 0.025 0.025 ÷3.3 ÷1.2
≥ 83
58 ÷ 72
≥ 72
≥ 82
95 ÷ 120
55 ÷ 80
≥ 65
≥
≥
14 30
≥
≥
14 30
≥ 23
≥
≥
14 40
≥
≥
15 40
≥
≥
13 40
≥
≥
14 45
≥
≥
10 25
≥
≥
14 35
≥ 590
187 ÷255
≥ 590
187 ÷255
≥ 780 (≥8)
≥810
≥ 392
≥ 491
(≥ 3.5)
≥ 590
207 ÷293
Where: s 0.2 – yield point, s B – ultimate strength, d – elongation, ? – reduction of area, KCU – impact strength for speciments with U-notch at 20 ºC, KCV - im act stren th for s eciments with V-notch at 20 ºC, HB – Brinell hardness.
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Ref. ? 1
2 3 4 5
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Object Moving blades: HPC governing stage Moving blades: (2-11) HPC stages Stationary blades: (2-11) HPC stages Moving blades: (12-20) HPC stages Stationary blades: (12-20) HPC stages
Material 18X? ? ? ? ? (? ? 291) 08X16H13M2? (? ? – 680) 15X11? ? 15X11? ? 20X13? 2X13
6
HPC outer casing
15XM1? ?
7
HPC inner casing
15XM1? ?
8
Nozzle boxes
15XM1? ?
9
HP rotor
?2? ?
Chemical analysis (elements, percent) C 0.060.12 0.110.20 0.110.20 0.110.20 0.50.26 0.160.24 0.140.20 0.140.20 0.140.20 0.210.29
Mn
Si
0.6-1.0
<-0.6
<-1.0
<-0.8
15-17
<0.50 <0.50
<-0.6 <-0.6
<-0.70 <-0.70
0.6-0.9 0.6-0.9 0.6-0.9 0.3-0.6
Cr 1011,5
1011.5 1011.5
Mo 0.81.1 2.02.5 0.580.82 0.580.82
V 0.20.4
0.230.42 0.230.42
<-0.6
10-14
-
<-0.6
12-14
0.20.4 0.20.4 0.20.4 0.250.5
1.21.7 1.21.7 1.21.7 1.51.8
-
Ti <-0.2 -
Nb 0.20.45 0.91.3
S
P
Ni
Cu
As
<-0.025
<-0.03
0.5-1.0
-0.3
-
<-0.02
<-0.35
12.514.5
<-0.3
-
-
-
<-0.03
<-0.35
<-0.6
<-0.03
-
-
-
<-0.03
<-0.35
<-0.6
<-0.03
-
-
-
-
<-0.025
<-0.03
<-0.6
-
-
-
-
-
-
<-0.025
<-0.03
<-0.6
-
-
0.91.2 0.91.2 0.91.2 0.91.05
0.250.4 0.250.4 0.250.4 0.220.32
-
-
<-0.025
<-0.025
<-0.3
<-0.3
-
-
-
<-0.025
<-0.025
<-0.3
<-0.3
-
-
-
<-0.025
<-0.025
<-0.3
<-0.3
-
-
-
<-0.025
<-0.025
<-0.4
<-0.20
-
Figure 20. Materials Applied and Chemical Composition for Upgraded HPC