ENCAP SP 3: Oxyfuel Boiler Technologies · Focus on PF and CFB boiler technology. 4 ... bituminous coal fired PF oxyfuel plants G De s t. DC W C DCA C ... Erection Operation Today

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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

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Outline

Introduction to oxyfuel combustion technology

Overview of the work performed in ENCAP

Main achievements and conclusions

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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

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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)

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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

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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

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Test facilities in WP 3.1

TC TC

TI

SC

FI

TI

FI

FI FI

FI

FI

PIC

TI

C3 H

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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

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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

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Highlights WP 3.1

Propane flame

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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

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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

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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

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CO2 avoidance

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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

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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

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WP 3.5 Oxyfuel combustion in 500 kWth test rig

Work packages 2

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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

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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.

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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

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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

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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