gas turbine seminar -17 - microsoft fatigue high-cycle fatigue ... state-of-the-art combined cycle...

Gas Turbine Seminar -17Lund University

Lund University / LTH / Energy Sciences / TPE / Magnus Genrup / 2017-10-03

Farligaste djuret?


Additive Manufacturing - AM


Almost 100% renewable in Germany W616


The European issue…


Cost of Electricity (CoE) vs. OH

×4

×2

Design

Courtesy of VGB Powertech

0.761

6000 6000t

0.961CoE

tCoE


The ”Duck-Curve”…

4.3 GW/h

California

Sweden


Grid codes


Flexibility

Star

t Steady state Active generation control

Spinning reserve off-peak turndown

SS

Shut

dow

n

Load

LF

Load

Cou

rtesy

of S

iem

ens


Flexibility

• Start-up– Air attemperation– Sky venting– Cascaded steam bypass with attemperation

• Ramping• Turn-down

– MECL

• Lock-out


GT start-up


Emissions vs. firing level

0 10 20 30 40 50 60AFR = FAR-1

Incr

easi

ng

Incr

easi

ngCombustion temp, °C

CONOx

NOx formation rate

Temperature

Stoichiometric

1100 1300 1500 1700

Flame temperature vs air/fuel Temperature influence on NOx and CO

Rich Lean

Tmax

Typical optimum for design at AFR ≈ 30 (i.e. λ ≈ 2)


Min Emission Compliance Load – MECL

NOx

CO

Exha

ust t

empe

ratu

re, °

C

Emis

sion

s, m

ass/

unit

time

EGT

IIIIII

10 30 50 70 90

Maximum EGT

GT load, percent

MECL

Staging to prevent from:• Lean blow out (LBO)• Combustion dynamics


Ansaldo sequential (SEV)


Ansaldo (Alstom) GT36


Exhaust loss

0

10

20

30

40

50

60Optimum design Super-

sonic

c2

u

w2

aΔh

c2

smV 3

2cΔh

22

a

N.B. The figure is based on a certain exhaust size – a general figure should be based on the annulus velocity (VAN=Q/A) since:• Loss ~ rating or flow• Loss ~ 1/pressure• Loss ~ 1/area ~ 1/ stress

Turn-up region


Fatigue – low or high?

Life cycles, [n]

Stre

ss a

mpl

itude

, [σ a

]

Low-cycle fatigue High-cycle fatigue

Fatigue limit

σσa

σa

Time

Stre

ss

Failure

No failure – no crack initiation

105…7

Wöhler- or σ,N curve


Rotor stress – temperature gradients

T

r

TCenter

TAverage

TSteam

TSurface

ΔT

y

i i

r

r

r

r2i

2y

2i

2

2r drrTdrrTrrrr

rμ1Eαrσ

y

i i

r

r

r

r

22i

2y

2i

2

2θ TrdrrTdrrTrrrr

rμ1Eαrσ

rim

r

0

r

022

rimr r

r13ΔTEαdrrT

r1drrT

r1Eαrσ

rim

rim

r

0

r

022

rimθ r

r213ΔTEαTdrrT

r1drrT

r1Eαrσ

rim

Temperature induced stresses (radial and hoop):

Simplified equations for a case without a bore:

α = 1.8∙105 °C-1

E = 6.9∙104 MPaΔT = 55 °Cσ@r=0 = 46 MPa

Example


Compressor blade failure


Siemens SGT5-8000H


Turbine flow path – typical 3-spool aero

Rolls-Royce: The Jet Engine


State-of-the-art combined cycle – GTCC

Combustor

~ 600°C (+) steam admission

~ 0.02 bar(a)

COT ~ 1,500°C (+)PR ~ 19…25

~ 40%

100%

GTHRSGSCGTCC η1ηηηη

SCR

~ 20%

Compressor Turbine

~ 625…680°C

~ 1.4…1.5 kg/MWs


Siemens HL-class

Courtesy of Siemens

• 42% efficiency• 85 MW/min• 1000 kg/s• 680 °C EGT


Siemens HL-class rotor #1

NuL

1~hPr,...Re,fkhL

transferheatConductivetransferheatConvectiveNu

Courtesy of Siemens


Siemens SGT-800


GE LM9000Simple Cycle CC & CHP Mechanical Drive• Free power turbine (2400…3780 rpm)

ISO Performance Maintenance Emissions• 65 MW power output• 43% simple-cycle efficiency• 99% availability• >80% cogeneration efficiency• 33:1 pressure ratio• 12,000 hours: inspections• 36,000 hours: hot section replacement• 72,000 hours: overhaul• Package design allows engine swap in 24 hours• 15 ppm DLE NOx & 25 ppm CO• DLE 1.5 dual fuel (natural gas and liquid fuel)

Fuel flex• 30…54 MWI gas

4 stage LPC

9 stage HPC2 stage HPT

1 stage HPT

4 stage HPT


SGT-A45 TR


P&W FT4000

Performance• 140 MW nominal output in twin-engine configuration• Wet compression for improved performance above

ISO conditions• Single or dual engine operation (common alternator)• 50 or 60 Hz performance with no penalty• 41% (+) thermal efficiency without external cooling

Operational• Less than 10 minutes start-up time• 30 MW/min ramp rate• Synchronous condensation with spinning PT, a FT has

a windage loss of 500…1,000 kW• NO maintenance penalty for start/stop!• Fleet has 17,500 OH’s and 1400 cycles

P&W has substantial experience in synchronous condensation without SSS-clutch!

>900 engines>20 years>40 MOH


Ventilation work – spinning PT

• The spinning power turbine will feed work into the ”entrapped” air by increasing the angular momentum

• It is “standard” to assess the work with the equation from the book by Traupel:

• The preceding equation shows why only non-geared PTs can be operated at nominal speed in ventilation

!!!82~

1

3

250@

500@

3222

V

V

V

PP

ulDCP


Firing level


Firing temperature – the misery factor…

• Creep follows an Arrhenius type of expression…– The Larson-Miller parameter:

– A more convenient and practical approach is to introduce a maintenance factor – MF (consumed life per hour of operation)

208.1102

2321

3

~10

lnln

10log20

ANANK

KKKP

tTP

Taperc

ccML

MML

Firing Lifing MF850 40000 1860 20000 2870 10000 4880 5000 8

COTeMF 0693.0


Creep – Larson-Miller parameter

975 1056 1138 1219 @40000 C.R.S


Lifing

Dtt

NN

rf

• It may be argued that creep-induced damage will reduce the fatigue life of a metal, and that fatigue-induced damage will reduce the metals creep life…

• One approach is to use the linear damage summation (DS) model (also called the linear life fraction, or linear cumulative damage) for assessing creep-fatigue-life: Dfatigue + Dcreep = Dtotal

• By combining the Robinson Rule (1952) for creep and Miner for fatigue, one gets the cumulative damage index (failure at unity):

This is the rationale behind the concept of ”equivalent operating hours”


The expensive way – equivalent hours…

LCF

n

Trips

n

rateloadstarts

oxidationandcreep

OH

firingfuel

tripsstarts

FFFFFEOH 111111

Where:EOH equivalent operating hoursOH actual operating hoursFfuel factor depending on fuelFfuel factor depending on firing levelnstarts number of “fired” startsFstarts number of hours per startFload rate load rate factor


LifingM

iner

-Pal

mgr

en

RobinsonD

Nt

NN

rf


Operational hours

Factored Hours = (K + M I) (G + 1.5 D + Af H + 10 P)

Actual Hours = (G + D + H + P)

G = Annual Base Load Operating hours on Gas FuelD = Annual Base Load Operating hours on Distillate FuelH = Annual Operating Hours on Heavy FuelAf = Heavy Fuel Severity Factor (Residual = 3 to 4, Crude = 2 to 3)P = Annual Peak Load Operating HoursI = Percent Water/Steam Injection Referenced to Inlet Air FlowM&K = Water/Steam Injection Constants (see GE documentation)

hoursHours ActualHours Factored

24000 intervaleMaintenanc


Noff cycles

• Actual Starts = (NA + NB + NP)• S = Maximum Starts-Based Maintenance Interval (Model Size Dependent)• NA = Annual Number of Part Load Start/Stop Cycles (<60% Load)• NB = Annual Number of Base Load Start/Stop Cycles• NP = Annual Number of Peak Load Start/Stop Cycles (>100% Load)• E = Annual Number of Emergency Starts• F = Annual Number of Fast Load Starts• T = Annual Number of Trips• aTi = Trip Severity Factor = fcn(Load, Trip during accel. = 2, Peak = 10) • η = Number of Trip Categories (i.e. Full Load, Part Load, etc.)

η

1iiTiPBA T1aF2E20N1.6NN0.5 Starts Factored

StartsStarts ActualStarts Factored

900 intervaleMaintenanc


Turbine governor – twin-shaft

n,...PR,,COTfEGT Nomcontrol

Courtesy of Siemens

s

T 44142

5

P4

P5

n1n

5

4

1η

5

4

5

4x

pp

pp

TT

p

γγ


Performance modelling

4 8 12 16 20 24 28 32 36 40Mass Flow W25RSTD [kg/s]

.8

1.2

1.6

2

2.4

2.8

3.2

3.6

4

P3q2

5 H

PC P

ress

ure

Rat

io

HPC

N=0.5

N=0.6

N=0.7

N=0.75

N=0.8

N=0.85

N=0.9

N=0.9 5

N=1

N=1 .05

0.86 0.85

0.84

0.82

0.80

0.75

0.70

Not converged points are marked with a red symbol.

44 48 52 56 60 64 68 72 76W48*sqrt(T48)/(P48/Pstd) [Kg/s]

1

1.5

2

2.5

3

P48q

5 P

ower

Tur

bine

Pre

ssur

e R

atio

LPT

N=0.6

N=0.7

N=0.

8N=

0.9N=

1N=

1.1

N=1.

2

0.9

4

0.93

0.92 0.90

0.88 0.85

0.80

Not converged points are marked with a red symbol.


Some results…

848 856 864 872 880Burner Exit Temperature T4 [C]

1818

.519

19.5

*10 3

Elec

tric

Pow

er [k

W]

02

46

810

1214

2.71

828^

(0.0

693*

(ZT4

-850

))

9810

010

210

410

610

811

011

2R

elat

ive

Torq

ue [%

]

.998

11.

002

1.00

41.

006

1.00

81.

011.

012

Rel

. HP

Spoo

l Spe

ed

Burner Temperature ZT4 = 850 ... 880 [C]


Impact on output from firing and ambient

848 852 856 860 864 868 872 876 880 884Burner Exit Temperature T4 [C]

14

16

18

20

22

24

26

28*10 3

Elec

tric

Pow

er [k

W]

Burner Temperature ZT4 = 850 ... 880 [C]Ambient Temperature Ts0 = -30 ... 30 [C]

Inlet Temperature T2 [C] = -28...32

-28-24-20-16-12-8-40481216202428

-28

-24

-20

-16-12

-8

-404

8

1216202428

ZT4 = 850 ZT4 = 855 ZT4 = 860 ZT4 = 865 ZT4 = 870 ZT4 = 875 ZT4 = 880


Flat rate @18 MW

-40 -20 0 20 40Inlet Temperature T2 [C]

700

725

750

775

800

825

850

875

900

925

Burn

er E

xit T

empe

ratu

re T

4 [C

]

.295

.3.3

05.3

1.3

15Th

erm

al E

ffici

ency

-40

48

1216

2024

2832

2.71

83^(

0.06

93*(

ZT4-

850)

)

Ambient Temperature Ts0 = -30 ... 30 [C]


Emulsionseldning

gas turbine seminar -17 - microsoft fatigue high-cycle fatigue ... state-of-the-art combined cycle...

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