gas turbine seminar -19 - energiforsk.se€¦ · gas turbine combined cycle -gtcc • gas turbine...

Gas Turbine Seminar -19Lund University

Lund University / LTH / Energy Sciences / TPE / Magnus Genrup / 2019-09-26

December 2017…


German and European wind power – VGB

Courtesy of VGB, ”ELECTRICITY GENERATION 2018|2019 – Facts and Figures


German wind power – VGB

Courtesy of VGB, ”ELECTRICITY GENERATION 2017|2018 – Facts and Figures


Flexibility

Load

Star

t Steady state Active generation control

Spinning reserve off-peak turndown

SS

Shut

dow

n

Load

LF

Cou

rtesy

of S

iem

ens

• Primary frequency response Speed droop Spinning reserve Automatic and fast

• Secondary frequency response Spinning/non-spinning reserve 30 s start, full capacity <15 min Frequency restoration

• Tertiary reserves

Rating


Flexibility

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

• Ramping• Peak

– Firing level– Compressor flow– Inlet cooling– Wet compression

• Turn-down– MECL– EGR/Inlet heating– Variable PT

• Lock-out

LoadSt

art Steady state Active generation control

Spinning reserve off-peak turndown

SS

Shut

dow

nLoad

LF


GT & GTCC – large gas turbine start-up


GE LM6000 Hybrid EGT

250 ms

5 min

10 MW (4.3 MWh) Li-Ion BatteryAttributes without fuel burn:• Instant (250 ms) response, always ready• 50 MW of operating reserve• Primary frequency response (FCR-N)• 5…-8 MVAR voltage support• 134 MWs inertia with synchronous condensing• Black start technology• Demand charge savings (?)Attributes with fuel burn:• 50 MW peaking power• 25 MW of high-speed frequency regulation• 10 MW peaking power• Self-managed BESS state of charge

Typical cost figures (Lazard):• Battery 190…442 USD/kWh• Converter etc. 60…151 USD/kWh


Grid codes

• UK National Grid Code (NGC):– Nominal power down to 49.5 Hz– Stay on-line with pro-rata output down to 47 Hz– Stay on line up to 52 Hz with reduced output (68 percent)– Brown-out requirements e.g. 0V for 0.14 s– Response rates

• Nordic– Stay on-line down to 47.5 Hz (30 minutes)– …


Speed droop – load and frequency relation

0 50 100

50

51

52

49

48

Freq

uenc

y, H

z

Load, %Normal (4 %) droopDead band & 6 % droop“Zero” droop – island operation

0 100 %

nom

ffDroop d PP

0

regulating

nomgen

P

PP fd f

“Regulating power”

Speed drop is defined as:

Recast to yield the convenient form:


Multiple alternators – power response

0 100 %

nom

ffDroop d PP

Freq

uenc

y, H

z f0f

ΔP1 ΔP2

P10 P1 P20 P2

Power output, MW

d1 d2

d1 > d2

100nomregulating

nom

PP f P fd f


Inlet fogging and wet compression

• Inlet fogging – all water evaporates before the blading Hot and dry sites

• High-fogging – water evaporates within the compressor Reduced blade lifing because of erosion

Figu

res

cour

tesy

of:

Jans

ohn

et a

l, “M

oder

n G

as T

urbi

ne S

yste

ms”


COE


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 FT8

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

360 USD/kW – 24,750,000 USD


Cost of Electricity – COE

var

Capital Fuel Maintenance

fix

Operation

OMf money unitCOE OMH P

CAPEXP H kWh

var ,1

Emissions Replacement capacity

nc efix

i p iieff eff eff eff eff

S P S EOMCAPEX fCOE OM c mP H P H P H

3 00

/

0.947817 10 3.6293.071MJ kWhMMBtu MJUSD MMBtu

f kf f k USD kWh

1,

1 1

N

N

i ii N

i

Where:

0.124

4 0.43

3700 578360 9.3 10

C SP

P U D kWP

APEX

3var

3

3.0...3.5 10

10...15 0.50...1.50 10installed

per annum

OM USD kWh

OM USD kW USD kWh

CAPEX Capital Expenditure

β Annuity factor

P Power

H Annual operating hours

f Fuel cost [USD/kWh]

i Interest rate

N Number of years

OMfix Fixed OM-spending [USD]

OMvarVariable OM-spending [USD/kWh]

COE = CAPEX + OPEX

10 percent interest rate (i) and 25 years (N) gives β = 0.11

N.B. All OM costs are engine dependent! One may(typically) expect a service cost equivalent to a newengine during 80,000 operating hours.Simple cycle

GTCC


Lazard’s data


The expensive (?) way – equivalent hours…

1 1 11 1 1

tripsstarts nnOH

fuel firing starts load rate Trips

creep and oxidation LCF

EOH F F F F F

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

Robinsonf r

N t DN N


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


Number off 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

900Maintenance interval Starts

Factored Starts Actual Starts


The service market

• Approximately 40,000 non-flying units• The total service market was 23.9 BUSD 2017

– Expected annual growth is 8…9 percent until 2025 (41.6 BUSD)– Large OEM margins

• Loads of variants…


Gas Turbine Combined Cycle - GTCC

• Gas turbine load is primarily controlled by the compressor IGV/VSV for maintaining high firing

• Higher flue gas temp but same limitations in admission temperature to the steam turbine → spray cooling

• No gain in lifing due to part load since the engine is fired at almost nominal level with constant cf. load

• Factor of two for each 10°C → misery factor

HRSG HT-section

EGT vs. load

Max adm.

1p

dTdQ m c


Improved GTCC control strategy

• Control the admission temperature rather than firing with only a minute performance drop

• Lower firing level → improved part-load lifing• No hardware modifications – only safe control

modifications (watch out for rumble…)


Engine fundamentals


State-of-the-art-GT (Single-shaft)• DLE – Dual Fuel• >1,600 °C• Can-Annular• Axial fuel staging• Fuel flexibility• Fuel saturation

• 3D Aero airfoils• Multistage VSV• “Super Finish”• Field-replaceable blades

• >600 °C• 1,000 kg/s• <25 ppm NOx• >10 ppm CO• No toxic emissions

• Four-stage turbine• Single-crystal Ni-based super-alloys• TBC• 3D Aero vanes and blades• ACC• Advanced film cooling• Micro-channel cooling

• Hydrogen cooled• 99 % Efficiency• 600 MW

• Welded rotor• Bolted rotor• Hirth-coupling• Hydraulic ACC

Future enablers (short term)• 1,700 °C• Ceramic matrix components• Additive manufacturing (AM)• Data analytics• Controls and optimization• No vane #1


Single- vs. multi-shaft industrial I

• Only power generation (torque issues)

• Part-load (pro’s and con’s) –effective way of controlling engine flow

• Exhaust size limitations (lower speed or high outlet velocity)

• Efficient exhaust• 50/60 Hz direct drive for large

units• Beam rotor with two bearings

• Both power and driver • Part-load (pro’s and con’s)• Lower starter power• “Free” power turbine speed

(lower outlet velocity level)• Typically less efficient exhaust

(lower recovery levels)• Three-shaft aero-derivatives• PT over-speed risk at load

rejection


Single- vs. multi-shaft industrial II

• Physical speed set by grid and gear ratio (<100 MW)

• Locus of operation at different ambient temp’s with nominal firing could be seen as a “running line”

• Typically reduced surge margin ay high ambient temperatures (COT/T1)

• Grid code requirement of 6% under-speed at +50°C – may be problematic!

• Typical speed range 60…105 %• Compressor speed is decoupled

from load• The running line is, more or less,

a function of firing – not ambient temp – for a certain engine

• No real grid code issues

N/√T

m*

PR

ISO DPN/√T

m*

PR

Power

ISO DP


Compressor and grid code…

• Grid code requires only speed (47 Hz) and temperature variation• Fouling has to be taken into consideration• The load shall be nominal down to 49.5 Hz and then “pro rata” with

frequency (hence over-firing or extra IGV) down to 47 Hz (UK)

1.081.041.000.960.920.880.840.80

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

Normalized relative flow

Nor

mal

ized

pre

ssur

e ra

tio Surge line

Locus of nominal firing

100 % N/T0.595 %89 %

88 %

5%@50°C 6%@47 Hz

Design point

1%

Based on Wolfgang Kappis, ”Compressors in Gas Turbine Systems, in ”Modern Gas Turbine Systems”


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

IGV

clos

ed

GT load, percent

MECL

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

UHC

Nominal firing

Base

d on

Gül

enin

Gos

wam

i”En

ergy

Con

vers

ion”

, 2nd

ed.


-15 0.7

-10 0.8

-5 0.9

Inlet guide vane – single shaft unit

-30° -20° -10° 10°

des

desm m

des desm m Close Open

Design point

Based on: Farkas F., “The Development of a Multi-Stage Heavy-Duty Transonic Compressor for Industrial Gas Turbines”, ASME 86-GT-91

Turn-down to 45 percent mass flow at design speed has been demonstrated


Typical preliminary design – single shaft

Shaft speed set by grid (50 or 60 Hz)

Exhaust temperature (COT) 870…950 K

Inlet H/T ratio ≈ 0.55Outlet H/T ratio ≤ 0.92

Firing temperature (COT) 1,600…1,900 K

Stage #1 rim speed = 400…425 m/sTip Mach # ≤ 1.3

Optimize:• Loading• Flow fcn (H/L)• Reaction• Stress

LOAD

0.50mc u

0.65mc u

AN2

Cp=f(AR, α, …)3000 (or 3600) rpm S.F. = 1.2


Typical preliminary design – single shaft

Shaft speed set by turbine AN2 and exit M#


Firing temperature (COT) 1,600…1,800 K



LOAD 0.50mc u

0.65mc u

AN2

Cp=f(AR, α, …)


Typical preliminary 2-S design choices• GG Speed set by flow@3000 (850…1000@3000)• Flow• COT (firing)• Pressure ratio

LOAD

Speed?Speed?

• Stage count*• Flow path shape/size• Stress/lifing

Gas generator

Performance

Power Turbine

*Single-stage CT is only possible below PR = 18


Typical preliminary design – gas generator


Firing temperature 1,600…1,800 K


Compressor Power + Losses = Turbine Power

Optimize:• Loading (H/L)• Flow fcn• Reaction• Stress


Optimum ITD area ratio ≈ 1.3

0.65mc u 0.50mc u


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 model by Traupel:

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

• The trick:

32 2 2

3@500

@250

1

2~ 8 !!!1

V

V

V

P C D l u

PP

I.e. if one assumes 600 kW at 3000 rpm then the windage power at 6000 rpm will be 4,800 kW!


Synchronous condensation

Twin-shaft with spinning PT

Twin-shaft with SSS-clutchSingle-shaft with SSS-clutch

• Synchronous condensation without firing Spinning PT? SSS-clutch Faster starts and less starter power

• Massive flywheel for increased inertia?

• Inertia in a future grid <4 m/s?• Power absorption

Single shaft compressor issues? Gearbox (forcing)

• Spinning PT – fast start• 600…900 kW windage, i.e. only non-

geared PT’s (~speed3)• P&W FT8, P&W FT4000, GE LMS-100,…

Flyw

heel


The technology S-curve

Existing technology curve

The breakthrough!

Existing technology advancement

Diminishing returns!

New technology introduction

Time

Figu

re o

f mer

it Time

USC

Effic

’y

Infancy Expansion Maturity

LMS100J-class

Effic

’y


?

Effic

’y


Based on Gülen in Goswami ”Energy Conversion”, 2nd ed.

New technology curve!• Hydrogen

Fuel cellGas turbine

• Fission energy?• Low-temp geothermal• Solar• Massive wind + storage


Vad är egentligen framtiden?

• Vi kommer till 65 procent verkningsgrad?• Mer el i framtiden…• Ångturbiner begränsas till 700°C (?)

– Max EGT 725°C– Keramiska skovlar?

• MHPS har sålt en trycksatt SOFC med 72 % verkningsgrad

– En bränslecell är ingen värmemotor och behöver inte fundera på Carnot…

• Pressure gain combustion?• Ingen ledskena #1• CCS?

– Post-combustion och flexibilitet?– Bättre med OxyFuel?


New carbon-free fuels

• Hydrogen• Ammonia

– How?– NOx-issue!


Hydrogen

“…I believe that water will one day be employed as fuel, thathydrogen and oxygen which constitute it, used singly or together,will furnish an inexhaustible source of heat and light, of anintensity of which coal is not capable…”

Jules Verne – The Mysterious Island (L’Île mystérieuse), 1874


Hydrogen – possibilities for power

Natural gasSMR (Steam

Methane Reforming)

Electrolysis

Wind power

Solar power

Water

CCS

H2 Pipeline H2 Storage

CO2

H2

Conversion to synthetic CH4

Natural gas

Carbon

Conversion to liquid ammonia

N2

Conversion back to H2

Storage

NH3

Grid

H2

inje

ctio

n

Zero-emission power plants*

Intermittent renewable power production:

*64% (+) efficiency for GTCC

• Wobbe index?• Flame speed?• Loads of home appliances!

9:1!!!


NOx – Water emulsion

60 80 100 120

20

40

60

80

100

NO

x @

15 [p

pmvd

]

Unit load [%]20 40 80 100

0.00.2

WFR [%]600

0.40.60.8

1.0

1.2

NO

x/N

Ox d

ry[-]

Dry Wet

20.2 1.41WFR WFRwetNOx eNOx

Based on: Lechner and Seume, “Stationäre Gasturbinen”, figures 10-14 and 10-16

Lefebvre 9.6:


State-of-the-art combined cycle – GTCC

Combustor

~ 600°C (+) steam admission

~ 0.02 bar(a)

COT ~ 1,500…1,650°C (+)PR ~ 19…25

~ 40%

100%

1CC GT SC HRSG GT

SCR

~ 20%

Compressor Turbine

~ 625…680°C

~ 1.4…1.5 kg/MWs


The combined cycle – GTCC

Entropy, s

Tem

pera

ture

, T Gas turbine expansion

Rankine

BraytonSteam turbine expansion

Condenser

COT

EGT

N.B. Schematic!

EvapEco

SHTem

pera

ture

Q m h

Exergy destruction ~ shaded area

TTD

PPT


Exergy by heat transfer – QChengel and Boles chapter 8

T1 T2

1

QT

2

QT

0

2

1 TQ

T

0

1

1 TQ

T

Heat:

Entropy:

Exergy:

Temperature:

EvapEco

SHTem

pera

ture

Q m h

Exergy destruction ~ shaded area TTD

PPT

01heatT

X QT

01heatT

X dQT

Q Q


Basic Eco-Reboiler coupling

1

2

3

4

53

5

66 7 8

9

a b

c

d e 1. GT2. HRSG3. ST4. Condenser5. Alternator6. FGC7. Absorber8. Regenerator9. Reboiler


Economizer-Reboiler Coupling

T

Q

Feed water temperature

Increased heat recovery

1

p

dTm cdQ


Plant performance – Summary

Single-pressure

conventional reboiler

Single-Pressure

Single-Pressure Reheat

Dual-Pressure Reheat

Triple-Pressure Reheat

Chilled Ammonia

Single-Pressure with

Reheat

Triple-Pressure Reheat

conventional reboiler

% 49.79 50.80 51.50 51.81 51.76 52.27 51.62

MEA MEA MEA MEA MEA NH3 MEA48.00

49.00

50.00

51.00

52.00

53.00

Eco-Reboiler


Reserver


Cycle performance – Carnot analogy

T

s

Higher PR

Lower PR

33’

2’

2

4’

4

1

3

1

3

1 1Lcarnot

H

T TT T

3 2 3 22 3

3 2 3 2

1

2 1

4 1 4 14 1

4 1 4 1

1

4 3

4 1

2 3

ln

ln

1TH

h h T TTs s T T

T T PRh h T TTs s T T

T T PR

TT

0.75...0.8GT TH

Carnot factor

2 3T

2 3T

4 1T

4 1T


Cycle thermodynamics – Sir John Horlock

T1

T3

1

2

3

4

Unavailable heat rejection loss

Expansion irreversibility

Compression irreversibility

3 2 3 22 3

3 2 3 2

4 14 1

4 1

ln

ln

p

p

in

in c

c

h h T TQTs s T TdQ

TT TTT T

2 3 4 1

3 1

1 1in outT TT T

2 3 2 31

3 4 1 4 1

in

out

T TTT T T

2 3 4 1

outinin out

QQT T

1in

out

4 1

2 3

1

3

1 1

1 1

out out

inin

out out

in in

Q TTQTT

Cycle widening (internal irreversibility):

External irreversibility:

Hence:Tref

T

S


Grid stability

𝜏𝐸

𝑃1 2⁄ · 𝐼 · 𝜔

𝑃 1 2⁄ · 2 · 𝜋 · 𝑓 ·𝐼

𝑃 𝐽

𝐽 𝑠⁄ 𝑠

The inertia constant:

The inertia constant is typically within the range of 5 and 10 seconds:

Nominal power = 500 MW5 s. 2500 MJ10 s. 5000 MJ

500048 ·

10.4 260 𝑘𝑔

Energy required during a start @ 5000 MJ, as 48 MJ/kg natural gas:

This is equivalent of some 280000 cups of tea!

Production means Inertia constant [s]

Nuclear 6.4

Hydro 3.4

Thermal 2.8

Wind- and PV power 0

HVDC import 0


Grid stability

1 2 109876543

Grid demand (4500 MW)

10 units á 500 MW running at 90 % load – 4500 MW

𝑓 𝑡 𝑓∆𝑃

𝑃 ·𝑓

𝜏 · 𝑡

0.00

10.00

20.00

30.00

40.00

50.00

60.00

0 20 40 60 80 100 120

Freq

uenc

y

Time

Speed/frequency vs. time @tau=10 s.

𝑑𝑓𝑑𝑡 @

∆𝑃2 · 𝜏 · 𝑃 · 𝑓


Grid stability – impact from inertia…

𝑑𝑓𝑑𝑡 @

∆𝑃2 · 𝜏 · 𝑃 · 𝑓

𝑑𝑓𝑑𝑡

∆𝑃 𝑎100 · 𝑃 · 𝑓 𝑓

𝑃𝑃 · 𝑓 ·

12 · 𝑓 · 𝜏

gas turbine seminar -19 - energiforsk.se€¦ · gas turbine combined cycle -gtcc • gas turbine...

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