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FuelFuel
ENCAP SP 3: Oxyfuel Boiler Technologies
Marie Anheden, Vattenfall Research and Development AB
CASTOR-ENCAP-CACHET-DYNAMIS Common Technical Training Workshop
22 - 24 January 2008, IFP-Lyon
2
Outline
Introduction to oxyfuel combustion technology
Overview of the work performed in ENCAP
Main achievements and conclusions
3
Oxyfuel Combustion
Combustion of fuel with O2 instead of air flue gas consisting of mainly CO2 (about 85%(v) on dry basis)flue gas recycle to control the combustion temperature
The work in ENCAP SP3 is only related to Oxyfuel combustion of solid fuel such as bituminous and lignite coal and pet coke
Focus on PF and CFB boiler technology
4
Motivation for the work in ENCAP SP3Advantages of Oxyfuel combustion for coal
Based on existing boiler and steam turbine technologyCan take advantage of ongoing development to increase efficiency of conventional steam power plants
Opportunity to reach high CO2 capture rate and near zero emission to airRemoval of pollutants during CO2 clean-up and processing
Reduced boiler heat losses and compact boiler designNo bulk N2 in flue gas gives reduced heat lossReduced recycle rate gives reduced boiler size and cost
Availability of almost pure oxygen enables enhanced combustion control
Previous experience before start of ENCAP:Experience from glass- and metal industryTests in small-scale rigs (few kW up to few MWth)
5
Objectives of the work in ENCAP SP3Goal
To show that oxyfuel combustion of bituminous coal, lignite can reach a CO2 avoidance cost of 20 € per ton of CO2 by applying innovative design and utilise process integration opportunities
Objectivesto develop and validate oxyfuel combustion based power plants concepts for bituminous coal and lignite for a greenfield plant using PF or CFB boiler technology
To provide a conceptual boiler design and suggest its integration with a power generating plant to provide an economically competitive technology
To examine special issues related to oxyfuel combustion in laboratory and pilot scale to be able to accommodate for those in the plant design and mitigate risk
6
Work packages
WP 3.1 Fundamentals in Oxyfuel Combustion (Chalmers)
Combustion tests and in laboratory scale test rigs (20-100 kW). Temperature, compositionGas radiationDeposits, material and flue gas treatment aspects
7
Test facilities in WP 3.1
TC TC
TI
SC
FI
TI
FI
FI FI
FI
FI
PIC
TI
C3 H
8
O2
SC
air/O2/CO2 fan mixing pointO2/flue gas
Wet flue gasrecycle
Dry flue gasrecycle
Flue gascooler
Flue gascondenser
Air inlet
Stack gas
Cooling water
Primary/secondaryregister
Measurementports R1, R2...R7
Direct O2 injection
pre-heater
Pilot burner
Cylindricalfurnace
800 mm
2400
mm
Cooling tube 1/4
gas analysis (O2, CO2, CO, NOx, SO2)
char sampling
ceramic tubeO 200 mm
burner 0 m
primary airsecondary air
2,5 m
T1
T2
T3
T4
T5
carrier air
stack
candle filter
insulation
electrically heating
port for pyrometer measurements 1,55 m
feedingsystem
100 kW oxyfuel test rig at ChalmersGas and coal fired
20 kW test rig at U. StuttgartCoal fired
8
Highlights WP 3.1SO2, NOX
in ppmO2, CO2
in vol.-%dry LAUSITZ OXYFUEL
0
20
40
60
80
100
22:49 22:59Time
0
400
800
1200
1600
2000
LA_OXY_13_NOxSO2_2_22660-22753
Averages SO2 1145 ppm NOX 268 ppm CO2 93.0 vol.-%dry
O2 4.7 vol.-%dry
0
20
40
60
80
100
18:02 18:12 18:22Time
0
400
800
1200
1600
2000
LA_LUFT_SO2_C8_20940-21070
Averages SO2 583 ppm NOX 317 ppm CO2 14.6 vol.-%dry
O2 2.7 vol.-%dry
SO2, NOX
in ppmO2, CO2
in vol.-%dry LAUSITZ AIR
Example: comparison of gas concentrations at air and oxyfuel conditions with flue gas recirculation
10
Work packages
WP 3.3 Oxyfuel greenfield coal PF definition (Doosan Babcock)Conceptual design of greenfield oxyfuel PF plant based on advanced supercritical power plant technologyIntegration and optimisation in combination with economic evaluationOperational characteristics, RAM, risk analysisBoth bituminous coal and lignite
WP 3.4 Oxyfuel greenfield coal CFB definition (Alstom)Conceptual design of greenfield oxyfuel CFB plant based on advanced supercritical power plant for coal (and pet coke)Integration and optimisation in combination with economic evaluationOperational characteristics, risk analysisSpecial features for CFB boiler design have been addressedTest in small-scale CFB combustion test rig
11
WP 3.3 One of the investigated concepts for the 1000 MW oxyfuel German lignite plant
Same investigation has been performed for 380 MW Greek lignite and 600 MW bituminous coal fired PF oxyfuel plants
G
Dest
.
DCW
C
DCAC
N2 + H20
AshHandling
Unit 100Coal Ash Handling
(VAB/RW E)
Unit 200Boiler Island
(Alstom)
Unit 500ESP + FG Clean-up
(VAB)
Unit 1200 + Unit 1300Inerts removal(VAB)+
CO2 compression(Air Liquide)
Unit 700Steam Turbine Island
(Alstom)
Unit 1100Cryogenic ASU
(Air Liquide)N2 + H20
Air
Vapourcondensate
Condensateto steam cycle
Make-up water
H20
CO2 XX%
Inerts vent
Lignite
Molecularsieves
Steam
Water
Lignite
Ash
N2, NOx, O2, Ar
O2 + Ar
N2+H20
N2
TEG recirculation
Streams
IP s team to coal dryer
HP steam
To R/H
IP steam
Feed water
O2 + Ar
O2 + Ar
Flyash
Bottom Ash
Flue gas condensate
Water to DCWC
Feed water preheating
Preh
eate
d N2 t
om
olecu
lar si
eves
Mil l
Primary recyc le
Secondary recycle
Pneumatic fuel transport
ESPWet ESPFlue gas fan
TRIFLUXheat exchanger
Dried lignite
Flue gas condenser
Dehyd-ration
Condensedwater
High Level Conceptual PFD, 1000 MWe Lignite Fired Oxy-Combustion Power Plant
13
WP 3.3 – 3.4 Efficiency of air-fired and oxyfuel plantsNet efficiency (%LHV)
45
36
49
4142
34
44
37
0
10
20
30
40
50
60
600 MW PF bit.,ref.
600 MW PF bit.,oxy
1000 MW PF lig.,ref.
1000 PF MW lig.,oxy.
380 MW PF lig.ref
380 MW PF lig,oxy
445 MW CFBbit., ref.
445 MW CFB bit.oxy
600 MW PF bit., ref.600 MW PF bit., oxy1000 MW PF lig., ref.1000 PF MW lig., oxy.380 MW PF lig. ref380 MW PF lig, oxy445 MW CFB bit., ref.445 MW CFB bit. oxy
Efficiency drop of 7-9%-points
14
CO2 avoidance
19
17
22
21
18
16
2120
0
5
10
15
20
25
600 MW PFbit., ref.
600 MW PFbit., oxy
1000 MW PFlig., ref.
1000 PF MWlig., oxy.
380 MW PFlig. ref
380 MW PFlig, oxy
445 MW CFBbit., ref.
445 MW CFBbit. oxy
CO
2 av
oida
nce
(€/t)
CO2 avoidance cost (€/t, base case, 25 yCO2 avoidance cost (€/t, base case, 40 y
All studied cases approximately meet the targeted CO2avoidance cost of
20 €/t CO2under evaluated main conditions
WP 3.3 – 3.4 CO2 avoidance cost
Work packages 2
15
Work packagesWP 3.5 Oxyfuel combustion testing in 500 kW rig (U. Stuttgart, IVD)
Combustion tests in semi-technical scale (500 kWth)Combustion characteristicsNOx and SOx chemistryAsh, deposits, material exposure testsOperational testing, alternative designs etc. as preparation for larger scale demonstration
Conclussion
17
Work packages
WP 3.6 Oxyfuel validation (Vattenfall)Preparation for large-scale pilot plant demonstration of oxyfuel PF and/or CFB boilerDecision to focus negotiations of content of ENCAP phase 2 on pilot scale testing in Vattenfall’s 30 MWth oxyfuel pilot plant under construction in Schwarze Pumpe, GermanyPresently under final negotiation with ENCAP partners and EUTest planned to start during autumn 2008
18
WP 3.6 Oxyfuel validation
2009 2010 20112005 2006 2007 2008
Pre- and Order planning
Permission planning
Execution planning
Commissioning
Erection
Operation
Today
Vattenfall’s 30 MWth oxyfuel pilot plant in Schwarze Pumpe. Status September 2007.
19
Main achievements and conclusions ENCAP SP3: Oxyfuel combustion fundamentals
Combustion characteristics of oxyfuel combustion of 2 lignites and 2 bituminous coals have been studied in small scale combustion test facilities (20-500 kWth)
For PF plant, to achieve similar temperature profile as in air-firing requires higher overall O2-level (25-27%(v)) but will result in higher gas radiation intensityFor CFB tests have been performed up to 90%(v) O2 in oxidantNOx reduction possible through flue gas recycle and staged combustionNo major impact on burnout and CO level at furnace outletNo major impact on composition of ash and deposits detected
20
Main achievements and conclusions ENCAP SP3Oxyfuel power plant concept development
Conceptual designs of PF and CFB oxyfuel plants have been established (1st generation oxyfuel plants)
Furnace and boiler design – more compact than for airThe design of a CO2 compression and purification unit to reach the required <4% non-condensable components in CO2 productEconomic analysis indicate that the target of 20 €/ton CO2 avoided (year 2004 level) can possibly be reached for a nth plantProceedures for start-up and shut-down, load change have been suggestedSafety aspects, technical risks and resulting expected availability for a nth
oxyfuel plant
No show-stoppers have been identified
21
Recommendations for continued work
Continued experimental investigations in pilot (10th:s MWth) and demo (100th:s MWth) plants are required to gain more experience
including downstream flue gas clean-up and CO2 compression and purification
Component optimisation and integration to further improve performance