COMPARATIVE PERFORMANCE ASSESSMENT OF IGCC … · SNOX power absorption (fan) MW - 6.4 6.4 6.4 Dec....
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IFC 2012 22/05/2012 - Leipzig 1 International Freiburg Conference on IGCC & XtL Leipzig, Germany, 21-24 May 2012 COMPARATIVE PERFORMANCE ASSESSMENT OF IGCC AND USC PLANTS INTEGRATED WITH CO 2 CAPTURE SYSTEMS Giorgio Cau 1 , Vittorio Tola 1 , Paolo Deiana 2 1 DIMCM, Dept of Mechanical, Chemical and Materials Engineering, University of Cagliari, ITALY 2 ENEA , Agency for New technologies, Energy and Sustainable Economic Development, Rome, ITALY email: [email protected]
Transcript of COMPARATIVE PERFORMANCE ASSESSMENT OF IGCC … · SNOX power absorption (fan) MW - 6.4 6.4 6.4 Dec....
IFC 2012 22/05/2012 - Leipzig 1
International Freiburg Conference on IGCC & XtL
Leipzig, Germany, 21-24 May 2012
COMPARATIVE PERFORMANCE ASSESSMENT OF
IGCC AND USC PLANTS INTEGRATED WITH CO2
CAPTURE SYSTEMS
Giorgio Cau1, Vittorio Tola1, Paolo Deiana2
1DIMCM, Dept of Mechanical, Chemical and Materials Engineering, University of Cagliari, ITALY 2ENEA , Agency for New technologies, Energy and Sustainable Economic Development, Rome, ITALY
email: [email protected]
IFC 2012 22/05/2012 - Leipzig 2
Worldwide energy scenario
Increasing role in the global energy scenario of coal-fired plants: • Increase of oil price and oil supply problems • Reliability, security of supply, costs effectiveness of fuel and electricity
Use of coal increases emissions of air pollutant and CO2 • Research of technologies that can reduce emissions • Innovative and more efficient technologies • Clean coal technology (CCS)
Greenhouse gas emissions reduction has became priority due to global warning concern • World energy demand is expected to grow with an average yearly rate of 1.8%. • Increase of renewable sources contribution • Sustainable use of fossil fuels
IFC 2012 22/05/2012 - Leipzig 3
Analysis and modeling of coal-based power plants
Performance assesment of coal-based power plants based on most innovative technologies in the field of energy conversion and environmental protection • USC plants • IGCC plants
• Simpliest configuration without CO2 removal and compression sections • Complex configuration with CO2 removal and compression sections
The study is based on complex simulation models specifically developed through Aspen-Plus and Gate-Cycle commercial software. More specifically: •Aspen-Plus gasification process and conditioning and purification processes of syngas and flue-gas •Gate-Cycle power sections
IFC 2012 22/05/2012 - Leipzig 4
USC Plant
Operating conditions: Tmax = 610 °C pmax = 300 bar
Main performance: Pe = 459.2 MW g = 45.92%
Large-size steam plants (400-600 MW).
Regenerative Rankine cycle with steam SH and RH
p and T higher than H2O critical one
IFC 2012 22/05/2012 - Leipzig 5
SNOX System
No process waste
Preheating of boiler air • Catalytic reduction of NOx by NH3 NO + NH3 + ¼ O2 = N2 + 3/2 H2O • Catalytic oxidation of SO2 to SO3 SO2 + 1/2 O2 = SO3 • SO3 hydration to H2SO4 SO3 + H2O = H2SO4
WSAC Wet Sulphuric Acid Condenser
Simultaneous DeNOx and DeSOx
USC Exhausts
GGHE
burner
IFC 2012 22/05/2012 - Leipzig 6
SNOX System Performance
60 70 80 90 100 110 120WSAC Temperature (°C)
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
H2S
O4 r
em
ova
l e
ffic
ien
cy
0.88
0.89
0.9
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
H2S
O4 m
as
s f
racti
on
in
co
nd
en
sa
te
H2SO4 removal H2SO4 mass fraction
10 15 20 25 30 35 40
GGHE minimum T (°C)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Bu
rne
r C
H4 m
as
s f
low
(k
g/s
)
0.45
0.451
0.452
0.453
0.454
0.455
0.456
0.457
0.458
0.459
0.46
US
C o
ve
rall
eff
icie
nc
y
CH4 mass flowUSC efficiency
98% SO2 removal 98% NOx removal
72°C WSAC operating temperature 98% H2SO4 removal efficiency 95% liquid H2SO4 purity
GGHE minimum ∆T influences methane mass flow in the burner and consequentely USC efficiency.
25°C GGHE minimum ∆T USC efficiency reduction of 0.4 percentage points
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CO2 Removal System
Absorber
Desorber
Chemical absorption Primary amine
MEA
Thermal energy from USC (LP steam extraction)
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CO2 Removal Section Performance
90% CO2 removal efficiency
Main operating parameters • Absorber temperature • Amine concentration • CO2 /MEA molar ratio
2 2.5 3 3.5 4 4.5 5 5.5 6
Solvent mass flow ((kg/sSOLVENT)/(kg/sFLUEGAS))
0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
CO
2 r
em
ov
al
eff
icie
nc
y
YMEA=30%; CO2/MEA=0.28
YMEA=25%; CO2/MEA=0.28
YMEA=35%; CO2/MEA=0.28
YMEA=30%; CO2/MEA=0.26
YMEA=30%; CO2/MEA=0.30
2 2.5 3 3.5 4 4.5 5 5.5 6Solvent mass flow ((kg/sSOLVENT)/(kg/sFLUEGAS))
2
2.5
3
3.5
4
4.5
Re
bo
ile
r d
uty
(G
J/t
)
YMEA=30%; CO2/MEA=0.28
YMEA=25%; CO2/MEA=0.28
YMEA=35%; CO2/MEA=0.28
YMEA=30%; CO2/MEA=0.26
YMEA=30%; CO2/MEA=0.30
0.6 0.7 0.8 0.9 1CO2 removal efficiency
2
2.5
3
3.5
4
4.5
Re
bo
ile
r d
uty
(G
J/t
)
YMEA=30%; CO2/MEA=0.28
YMEA=25%; CO2/MEA=0.28
YMEA=35%; CO2/MEA=0.28
YMEA=30%; CO2/MEA=0.26
YMEA=30%; CO2/MEA=0.30
0.7 0.75 0.8 0.85 0.9 0.95 1
Efficienza di rimozione della CO2
200
240
280
320
360
400
Po
ten
za
te
rmic
a a
l re
bo
ile
r (M
W)
YMEA=30%
T=35 °CCO2/MEA=0.28
IFC 2012 22/05/2012 - Leipzig 9
USC plant performance
USC USC + SNOX
USC +
Dec. 70%
USC +
Dec. 90%
USC power output MW 459.5 460.4 376.4 350.0
USC net efficiency % 45.95 45.57 37.25 34.65
Steam section power output MW 459.5 466.8 408.5 388.6
SNOX power absorption (fan) MW - 6.4 6.4 6.4
Dec. section power absorption (fan) MW - - 3.0 3.0
CO2 compression section absorption MW - - 22.8 29.2
Fuel chemical power input MW 1000.0 1000.0 1000.0 1000.0 Fuel chemical power input (natural gas) MW - 10.2 10.2 10.2
CO2 emissions kg/s 95.04 95.60 28.68 9.56
CO2 specific emissions g/kWh 744.6 747.5 274.3 98.3
IFC 2012 22/05/2012 - Leipzig 10
Texaco entrained bed gasifier
Syngas
in uscita
Scorie
Vapore
Acqua di
alimento
SlurryOssigeno
Gasification pressure 30 bar Coal mass flow 39.51 kg/s Coal weight fraction in the slurry 0.65 Oxydant/coal mass ratio α 0.94
O2 molar fraction in the oxidant 0.95
Temperature 1400 °C
Syngas mass flow rate 92.3 kg/s
Syngas LHV 7.75 MJ/kg
Gasifier cold gas efficiency 0.7235
Syngas molar composition %
CO 38.4
CO2 11.9
H2 23.5
H2O 24.0
N2 1.1
Ar 0.8
H2S 2260 ppm
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Gasification process
• gasification temperature • syngas LHV • cold gas efficiency • H2/CO molar ratio • syngas composition as a function of oxidant/coal mass ratio and slurry composition
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Oxidant/coal mass ratio
600
800
1000
1200
1400
1600
1800
Gas
sif
ica
tio
n t
em
pera
ture
(°C
)
6
7
8
9
10
11
12
Sy
ng
as
Lo
wer
He
ati
ng
Va
lue
(M
J/k
g)Slurry 70/30
Slurry 65/35
Slurry 60/40
Temp.
LHV
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Oxidant/coal mass ratio
0.6
0.7
0.8
0.9
1
Co
ld g
as
eff
icie
nc
y
0.4
0.5
0.6
0.7
0.8
0.9
1
H2/C
O m
ola
r ra
tio
Slurry 70/30Slurry 65/35Slurry 60/40
Temp.
LHV
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Oxidant/coal mass ratio
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Mo
lar
frac
tio
n i
n t
he
syn
gas
CO
CO2
H2
CH4
N2
H2O
IFC 2012 22/05/2012 - Leipzig 12
Main performance of combined cycle and gas turbine
Natural gas Syngas
Gas turbine Gas turbine power output MW 242.6 264.1 Gas turbine net efficiency % 35.49 37.66 Fuel chemical power input MW 682.7 701.3 Fuel mass flow kg/s 14.39 71.03 Fuel LHV MJ/kg 47.451 9.875 Cycle maximum temperature °C 1331.1 1313.5 Gas turbine pressure ratio 14.9 16.0 Exhaust temperature °C 622.2 614.0 CO2 molar fraction in exhaust 0.0412 0.0940 Combined cycle Combined cycle power output MW 382.0 409.2 Steam section power output MW 139.4 145.4 Exhaust mass flow kg/s 624.4 681.1 Combined cycle net efficiency % 55.95 58.40 CO2 emissions kg/s 40.10 92.45 CO2 specific emissions g/kWh 377.9 812.8
Combined cycle • GE PG9351 (FA) gas turbine • Triple level pressure HRSG • steam power plant based on 3 turbines (HP-IP-LP)
Switching from NG to syngas increases: • fuel mass flow in gas turbine • gas turbine power output • CO2 molar fraction in exhaust
Syngas fuelling increases: • steam section power output • combined cycle power output • CO2 specific emissions
IFC 2012 22/05/2012 - Leipzig 13
HRSG energy balance characteristic curves
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Heat Exchanged (MW)
0
100
200
300
400
500
600
700
Te
mp
era
ture
(°C
)
Flue gasH2O
NGCC
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Heat Exchanged (MW)
0
100
200
300
400
500
600
700
Tem
pera
ture
(°C
)
Flue gasH2O
IGCC-LSR
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350
Heat Exchanged (MW)
0
100
200
300
400
500
600
700
Tem
pera
ture
(°C
)Flue gasH2O
IGCC-LST
IGCC-LSR configuration Sub-cooled water from ECO IT-HP
IGCC-LST configuration Saturated water from ECO HT-HP
Syngas is cooled from 1400 °C to 400 °C in radiant and convective heat exchagers producing saturated steam for CC.
IFC 2012 22/05/2012 - Leipzig 14
CO2 Removal System
1. CO Shift conversion process
H2O/CO molar ratio = 1.2 CO conversion = 96% IGCC power reduction = 4.9%
2. CO2 removal process
Physical solvent (Rectisol) Energy requirements: •CO2 compression • Solvent refrigeration
IFC 2012 22/05/2012 - Leipzig 15
CO2 Removal System
CO2 absorption
Solvent regeneration
CO2 compression
Solvent pumping and freezing
IFC 2012 22/05/2012 - Leipzig 16
Syngas main characteristics
Exit Desulph. section
Exit CO-shift section
Exit Dec.
(removal 70%)
Exit Dec.
(removal 90%)
Mass flow (kg/s) 71.03 105.69 35.51 16.84 Temperature (°C) 270 200 270 270 Pressure (bar) 23.05 21.25 23.05 23.05 LHV (MJ/kg) 9.874 6.029 17.985 37.874 Msyng*LHV 701.4 637.2 638.6 637.8 H2 0.3157 0.5013 0.7622 0.8714 CO2 0.1496 0.3977 0.1620 0.0420 CO 0.5065 0.0116 0.0180 0.0200 N2 0.0143 0.0089 0.0130 0.0150 Ar 0.0087 0.0055 0.0080 0.0090 H2O 0.0050 0.0748 0.0360 0.0420 CH3OH - - 0.0008 0.0005
CO Shift section
IFC 2012 22/05/2012 - Leipzig 17
IGCC performance
IGCC-LSR IGCC +
DeC. 70%
IGCC +
DeC. 90%
IGCC power output MW 444.0 359.4 348.1
IGCC net efficiency % 44.40 35.94 34.81
Fuel thermal power input MW 1000.0 1000.0 1000.0
Combined cycle power output MW 487.9 439.5 437.3
ASU requirements MW 47.9 47.9 47.9
Gas turbine power output MW 264.1 246.6 243.9
Steam section power output MW 223.8 192.8 193.4
CO2 removal section penalties MW - 32.4 41.3
CO2 emissions kg/s 93.8 28.1 9.4
CO2 specific emissions g/kWh 767.4 281.9 97.0
IFC 2012 22/05/2012 - Leipzig 18
Conclusions
USC USC + Dec. 90%
IGCC IGCC + Dec. 90%
Plant power output MW 460.4 350.0 444.0 348.1
Plant net efficency % 45.57 34.65 44.00 34.81
CO2 specific emissions g/kWh 744.6 98.3 767.4 97.0
USC plant shows slight better performance than IGCC. Plant net efficency is 45.6% vs 44.0%. USC integrated with CO2 removal section shows a 11 percentage points of penalization on efficiency, lower penalization can be found for the IGCC plant (9.5 perc. points). CO2 specific emissions are very low and similar for both plants.
