TEP4115/4120 TermodynamikkTEP4115/4120 Termodynamikk

Kap 9: Gas Power SystemsKap 9: Gas Power SystemsDel 2

Olav BollandOlav Bolland

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Power production in Norway

• National grid: 99.5% hydropower– 27000 MW - 120 TWh/a– Per capita: 6 kW - 27000 kWh/a

• Offshore oil/gas: mechanical power and local gridsg p g– 3000 MW gas turbine power - 10 TWh/a

• Future:Future:– Wind power: 2002-2010 +3 TWh/a– More hydropower: potential YES y p p– acceptance NO– Natural gas power: potential YES

problem is CO2

– CO2 is a hot issue!!

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– Dependence on import of coal & nuclear power?

Kraftproduksjon og forbruk i Norgep j g g

150TWh/år

Variasjonsområde

130

140

150

Prod

Produksjon i normalår med produksjonsapparat som i 2000

Variasjonsområde for produksjon

110

120Prod

Forbruk

Forb -kjeler

80

90

100Forb.-kjeler

Normalår

70

80

1975 1980 1985 1990 1995 2000År

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Gas Turbines

Fi 9 8 389

Assumptions for the basic gas turbine cycle:Ai id l i th ki fl id th h t

Fig. 9.8, page 389

• Air, as an ideal gas, is the working fluid throughout• Combustion is replaced with heat transfer from an external source

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Gas Turbine Applications• Aero Engines (jet, turbofan, turboprop)• Gas Pipelines (compressor driver)• Power plants (generator driver)Power plants (generator driver)• Combined Heat and Power (generator, utilisation of exhaust heat)• Ship Propulsion• Oil/Gas Platforms (generator & compressor driver)• Oil/Gas-Platforms (generator & compressor driver)• Others (emergency backup, desalination)

• 2000: Production value of aero engines larger than for gas turbines for power generation and mechanical driveg p g

• 2001 : Production value of gas turbines for power generation and mechanical drive larger than for aero engines

Annual production value of gas turbines/aero engines: 50 bill. US$

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General Electric LM5000 d k flLaget med utgangspunkt i flymotor

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Cutaway diagram of a Westinghouse 501D5A gas turbine

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Siemens V94.2ca. 150 MW,

første gassturbin med lav-NOXNOX = (NO/NO2) = nitrogenoksiderNOX = (NO/NO2) = nitrogenoksider

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Turbin i gassturbin4 t i Si4-trinns, Siemens

1. trinns løpeskovlerp

1. trinns ledeskovler

Ri b kRingbrennkammer(brennerne kan ikkesees bak til høyre)

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sees, bak til høyre)

Work closed/open systems

First law for a closed system:First law for an open system (steady-state):

dU2 1

Relating heat to entropy:

Q W U U 1 2

2 2 2

0

Relating heat to entropy:

dUQ W mh mh

dt

2

1

Q T dS

T dS dU PdV

2 2 2

1 1 1

and and

Q T dS dU pdV

T dS dU PdV T dS dH Vdp

2 2 2

1 1 1

T dS dU PdV

Q T dS dU pdV

2 2

1 1

H U pV dU dH pdV Vdp

Q dH V dp

2

2 1 2 11

U U pdV W U U 1 1

2 2

1 1

Q m dh V dp

22

1

W pdV 2

2 1 1 21

2

( ) ( ) 0m h h V dp W m h h

W V dp

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1

W V dp

The Brayton Cycley yCycle Analysis:

12W

12

1 2

Wh h

m

233 2

Qh h

m

m

34

3 4

Wh h

3 4h hm

411 4

Qh h

m

Fig. 9.9, page 389

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Ideal Brayton Cycley y

Fig. 9.10, page 391

Using Constant Specific Heats, the cycle thermal efficiency is:

11 1

2

1

1 k

kpp

Fig. 9.11, page 394

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1p

Ideal Brayton Cycle, different pressure ratios

Fig. 9.12, page 395

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Irreversibilities in a gas turbine cycleg y

Fig. 9.13, page 397

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Regenerative/recuperative Gas Turbinesg p

2

4 2

xreg

h h

h h

Fig. 9.14, page 400

Største gassturbin med rekuperator R ll R WR21 (20 MW)

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4 2h her Rolls Royce WR21 (20 MW)Rekuperator benyttes typisk på små GT, 100-500 kW.

Reheat and Intercoolingg

Fig. 9.16, page 404

Alstom GT26/GT24 (277/191 MW, 3000/3600 rpm)er de eneste gassturbiner som benytter reheat.Alstom bruker begrepet ”sequential combustion”.

Reheat, regeneration, and intercooling are most effective Fig. 9.18, page 407

lstom bruker begrepet sequent al combust on .

when used in combination with one another. However, weight limitations (e.g. aircraft

li ti ) ft li it th i

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applications) often limit their usage.

Aircraft Applications

Fig. 9.20, page 414

Turbo Jet Applications, with and without afterburner

Fig. 9.21, page 415

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Turbo jet – with afterburner

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Aircraft Applicationspp< 1000 km/t

< 600 km/t

a) Turboprop, b) Turbofan, and c) Ramjet applications

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Turbofan

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RakettmotorRomferge; i brun tank: oksygen hydrogen

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Compressible Flows: The Basics

2 1F V Vm

1-D Steady Flow Momentum Equation:

Velocity of Sound, isentropic wave, ideal gas: c kRT

Mach Number:V

Mc

Stagnation Enthalpy:

2Vh h Stagnation Enthalpy:

0 2h h

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Combined Cycle

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Fig. 9.23, page 419

Hvorfor har en kombinert prosesshøy virkningsgrad ?høy virkningsgrad ?

CARNOTlT

T 1

Carnotvirkningsgrad; en kvalitativ beskrivelse av virkningsgrad for en kraftprosessCARNOT

hTTl er temperatur for varmeavgivelse fra prosessenTh er temperatur for varmetilførsel for prosessen

Gassturbin prosess

K bi t

TTh

Th h

s sh

3 2

3 2høy

2

3

4 h h

Gassturbin prosess

TTh

Th h

s sh

3 2

3 2høy

h h4 1

Kombinert prosess

s

Tl

1

2 4

Th h

s sl

4 1

4 1høy

T h h3 2Dampturbin prosess Tl 1

2

3

4

Ts sl

4 1

4 1lav

s

Th

Ts sh

3 2

3 2lav -

2

3

Th h

s sl

4 1

4 1lav

s

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s

Tl 14

s s4 1

Utvikling av virkningsgrad for gassturbin-anlegg

70

Kombinerte gassturbin-/dampturbinanleggFlyderiverte" gassturbiner

60

65 Store industri-gassturbiner

50

55

grad

[%

]

Kombinerte gassturbin-/dampturbinanlegg

40

45

Vir

knin

gsg

"Flyderiverte" gassturbiner

30

35V

Store industri-gassturbiner

1954 1958 1962 1966 1970 1974 1978 1982 1986 1990 1994 1998 2002 200620

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1954 1958 1962 1966 1970 1974 1978 1982 1986 1990 1994 1998 2002 2006

Varmegjenvinning fra en eksosgass ved dampproduksjonved dampproduksjon

700

500

600Eksosgasskurve,stigningstall 1/(m*cp)

400

500

atu

r [C

]ra

ture Eksos/

Exhaust

pinch,minste dT i kjel,begrensende fordampprod ksjon

200

300

Tem

per

aT

emp

e Vann/DampWater/steam

fordamper,fordamping ved

dampproduksjon

100

Overheter,stigningstall 1/(m*cp)

fordamping ved konstant temperatur

economiser,stigningstall 1/(m*cp)

0

0 50 100 150 200 250 300 350

Overført varme [MW]H t t f

stigningstall 1/(m cp)

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Heat transfer

Components of a Vapor Power PlantSteam Power Plant

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Rankine Cycley

Turbine: Pump:Turbine:

1 2tW

h h

Pump:

4 3pW

h h

m m

Overall Performance:

Condenser (1 side):Boiler:

1 2 4 3/ /t pW m W m h h h h

h h

2 3outQ

h hm

1 4inQ

h hm

1 4/inh hQ m

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Combined Cycle Power Plant

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Gasskraftverk Kårstø - 420 MW

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Fuel characteristics for CO2-emission2

Fossil fuels consists of the combustible componentsCarbon (C) and Hydrogen (H)

M th C HM ethane: C H1 4

The ratio between carbon and hydrogen gives the amount of CO2

C H O CO H O2 2 2m n mn

mn

4 22 2 2m n

l il t l

m

n

m

n

m

n

4 2

coal oil natural gas

coal oil natural gas

n n n

11 0 5 0 25. . .

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Emission of CO2 from fossil fuels

110012001300

kWh e Methane (H/C=4)

Distillate oil (H/C=2)

90010001100

O2 p

er k Lignite (brown coal)

Bituminous coalAnthrasit

600700800

ram

CO

Anthrasit

300400500600

on o

f gr

100200300

Em

issi

o

30 35 40 45 50 55 60 65 70 75 80 85 90 95 100Eff iciency [%]

0

E

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Eff iciency [%]

”CO2-fri” gasskraft?Mest kjente teknologiprinsipperMest kjente teknologiprinsipper

CO₂

N₂/O₂

CO₂

s Power

Post-combustion

₂separation

CO₂

s, B

iom

ass

plant

CO₂ compression & conditioning

ShiftH₂ N₂/O₂

CO₂ compression & conditioning

Powerplant

Gasification

CO₂separation

H₂

CO₂

CO/H₂

Nat

ural

Ga

& conditioning

Power CO₂

& conditioningReforming

CO₂

CO/H₂

Coa

l, O

il, N Pre-combustion

Powerplant

O₂N₂

C

Oxy-combustion

Navn/begreper for de tre metodene:1 P t b ti

Air Air separation

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1: Post-combustion2: Pre-combustion3: Oxy-combustion (eller oxy-fuel)