Circulating Fluidized Bed Boiler Technology

A competitive option for CO capture through oxyfuel combustion?A competitive option for CO2 capture through oxyfuel combustion?

tIEA 1st Oxyfuel Combustion Conference, Cottbus, 9 September 2009

Nicklas Simonsson Vattenfall Research & Development ABNicklas Simonsson, Vattenfall Research & Development ABTimo Eriksson, Foster Wheeler Energia OyMinish Shah, Praxair Inc.

Vattenfall AB

Outline

1. Air CFB boiler technology Development trends Current state of the art Main principles and benefits

2. Hamburg CHP oxyfuel CFB conceptual design study Objective Design basis Design basis ASU and CO2 processing unit Boiler design

T h i l lt Techno-economical results

3. Summary and conclusions

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Air CFB Technology Development trendsgy p

Traditionally CFB boilers characterised by

Small unit sizes Low/moderate steam data

Unit Capacity (MWe)

500

600

800 800 MWeUnit Capacity (MWe)

500

600

800 800 MWe

Mainly used in applications with difficult to use fuels and biomass

Significant scale up of unit 300

400 Lagisza

JEA300

400 Lagisza

JEA g psize and increase of steam data during last decade

Today CFB technology must be considered a competitive0

100

200

Pilot Plant Oriental Chem

Turow 1

VaskiluodonNova ScotiaTri-State

General Motors0

100

200

Pilot Plant Oriental Chem

Turow 1

VaskiluodonNova ScotiaTri-State

General Motors be considered a competitive option also for large-scale utility applications

01970 1975 1980 1985 1990 1995 2000 2005 2010

Start-Up Year

01970 1975 1980 1985 1990 1995 2000 2005 2010

Start-Up Year

Source: Foster Wheeler

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Source: Foster Wheeler

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Air CFB Technology Current state of the artgy

Foster Wheeler Lagisza CFB unitFoster Wheeler Lagisza CFB unit

Worlds largest and first supercritical CFB boiler Handed over to customer in Poland in June 2009

460 MW

Th F t Wh l L i CFB b il f t l

460 MWe gross 275bar/560C/580C 290C feed water temperature >43% net efficiency

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The Foster Wheeler Lagisza CFB boiler from conceptual design to existing plant

43% net efficiency

Air CFB Technology Principles and benefitsgy p

Combustion of fuel in a high bed inventory consisting of a mixture of fuel, ashes and sorbent (limestone). Bed suspended or fluidised through air entering the bottom of furnace

Solid recirculation

Source: Foster Wheeler

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Hamburg OxyCFB CHP conceptual design studyg y p g y

Objective: To evaluate the competitiveness and possibilities p p

of CFB technology in oxyfuel applications

Study performed in close cooperation with:F t Wh l (b il d i ) Foster Wheeler (boiler design)

Praxair (ASU and CO2 compression)

Design basis:Design basis: Hamburg site conditions Bituminous coal (LHV 25.1 MJ/kg) 500 MWe grosse 0-400 MWDH (output and temperature levels

varying during the year) Both air and oxyfuel cases investigated

CO t t >90%

The Tiefstack CHP plant one of several units delivering district heating to the the city of Hamburg The Hamburg district heating network

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CO2 capture rate >90% Hamburg. The Hamburg district heating network consist of over 770 km pipelines.

Hamburg OxyCFB CHP conceptual design study

Included activities:

g y p g y

Conceptual boiler design, performance, cost and layouts for air and oxyfuel

ASU and CPU design, performance, cost and layoutslayouts

Flue gas cleaning options ASU O2 purity sensitivity and optimisation study

D t il d ll l t H&MB l l ti Detailed overall plant H&MB calculations Overall plant heat integration optimisation Plant Layout Economical evaluations Risk assessment

Fl h t f th H&MB l l ti ( b )

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Flow sheet from the H&MB calculations (above) and the resulting OxyCFB plant layout.

ASU and CO2 compression and purification unit designsdesigns Unit designs based on Praxairs state of the art

Air separation unit Dual trains with total capacity 7088 TPD O2 (contained)

@ 1.3 bar and 172C Optimisation study 97%-vol O2 purity selectedOptimisation study 97% vol O2 purity selected Low temperature heat recovery to DH network

CO2 processing unit Single train (with two parallel compression units) with

total capacity of 7860 TPD CO2 contained (inlet flue gas CO2 concentration ~85%-vol)

CO2 capture rate 93.3% CO2 product quality 96.1%-vol. @ 110 bar and 30C Low temperature heat recovery to DH network and

heat integration for vent gas expansion No provisions for SOX and NOX removal although

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No provisions for SOX and NOX removal although pursued by Praxair for future developments

Air- and oxyfuel CFB boiler designy g

Existing 460 MWe,gross Lagisza boiler design used as starting pointstarting point

Low mass flux BENSON once-through technology with vertical furnace tubes

Sliding pressure operation

Steam data representative for given time frame Steam data: 600C/620C /290 bar Feed water temp: 300C

Assumptions OxyCFB design (compared to AirCFB) HP steam flow kept constant Furnace velocities similar as in air firing Same flue gas excess O2 content (3.6%-vol, dry) Oxidant O2 so that adiabatic combustion temperature does

not exceed that of air firing Same Ca/S ratio

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Air ingress 1% of flue gas flow

OxyCFB process flow diagram flue gas sidey p g g

Vent gasesBypass eco

LP B

To stack

Boiler

DryingCompression

Conden-

serGas cleaning

Secondary RG preheater

Boiler eco

LP eco B

HRC

CO2

Fuel

H2O and soluble impurities

gas

Intrex

Recycle gases

RG preheater

HRS

AirASU

TransportStorage

Fluidizing gasPreheatersMixing

ASU

N2

Oxygen(97% O2)Mixing

Steam

Air

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Overall plant technical & economical key datap yAirCFB

CondensAirCFB

DH*OxyCFB Condens

OxyCFB DH*

Fuel input [MW] 1052 1052 1047 1047

Economical assumptions

Yearly operating time: 7500h Rate of interest: 6%(real)

Gross Power [MWe] 506 469 516 482

Net Power [MWe] 472 435 381 347

District heating [MWth] - 269 - 269

Net efficiency [%] 44.9 41.4 36.4 33.2

( ) Plant life: 25 years Coal price: 6.6 /MWh (incl.

transport & handling) (IEA WEO 2007)

District heating credit: 25 /MWh (EU b d NG i 8 /MWh)

Total efficiency [%] - 67.0 - 59.9

Specific invest. [/kWe net] 1621 1703 2952 3096

COE [/MWhe] 39.8 28.1 65.6 52.7

(EU border NG price + 8 /MWh) (NG=17 /MWh IEA WEO 2007)

Investments on Q3 2008 level and uncertainty of +/-30%

No cost for CO2 transport and storage included[ e]

CO2 avoid. cost [/ton CO2] - - 37.9 33.4storage included

DH can significantly improve plant economics

*Yearly average values due to varying DH output and temperature levels.

Slightly higher COE and CO2 avoid. cost compared to PF cases on equal basis. However: Uncertainties in investment costs between studies Not considered that CFB cases potentially could utilise lower quality fuels more cost effective

CFB ld ll b titi b th ith d ith t CO t !

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CFB could very well be competitive both with and without CO2 capture!

Hamburg OxyCFB study Summaryg y y y Established air CFB advantages also valid for

OxyCFB Fuel flexibility (Hard coal Lignite Biomass)Fuel flexibility (Hard coal, Lignite, Biomass) Possibility to use low grade/less expensive fuels SOX and NOX reduction without secondary

measuresSi l f l f di

Solidrecirculation

SolidrecirculationREACTOR REACTOR

CFB CFB

Simple fuel feeding system

Additional potential advantages in oxyfuel operation

Solidflow inSolid

Solidflow

Solidflow

flow in

High O2 concentration designs turbulent bed and heat exchanger arrangements provide good means of equalising temperature levels

Flexi-BurnTM Easier to enable same boiler to be a) Internal circulation b) External circulation

flowout out

Fluidizingair flow

Fluidizingair flow

operated with both air and oxyfuel firing No fuel pulverising no need for primary recycle

flow Furnace at overpressure easier to minimise air

The INTegrated Recycle heat EXchanger (INTREXTM) - an additional advantage in oxyfuel operation in terms of combustion temperature control

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Furnace at overpressure easier to minimise air ingress

control.

INTREXTM and Flexi-BurnTM are trademarks of Foster Wheeler AG

Hamburg OxyCFB study Summary

Disadvantages/issues:B il i l d ili ti li htl l l t ffi i

g y y y

Boiler island auxiliary consumption slightly lower plant efficiency Limestone consumption Ash flows and disposal issues Erosion of reactor walls although rare in new CFB designsErosion of reactor walls although rare in new CFB designs

Uncertainties, risks and development needs: So far only small scale OxyCFB test rigs (< 100 kW)So far only small scale OxyCFB test rigs (< 100 kW) Further validation in pilot and demo scale necessary (as for PF Oxyfuel) Uncertainties related to:

Ultra-supercritical steam data (> 600C) in both air and Oxyfuel operation In-bed SO2 capture in Oxyfuel operation Combustion control systems Heat transfer in Oxyfuel operation

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Vattenfall will continue to follow development of oxyfuel CFB technology closely!

Thank you!

For further information please contact:

Nicklas Simonsson

Vattenfall Research & Development AB

tel.: +46 (0)8 739 5561

nicklas.simonsson@vattenfall.com

Vattenfall AB

Back-up

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OxyCFB DH profiles efficiency distributiony p yElectrical and total efficiences in the operating profiles

80,0Yearly

67,966,1

61,158,860,0

70,0

Yearly average

29 731,7 33,4

35,4 35,633,2

49,8

35,640,0

50,0

f

i

c

i

e

n

c

y

[

%

]

29,7

10 0

20,0

30,0

E

f

f

0,0

10,0

Profile 1 400MW DH

Profile 2 360MW DH

Profile 3 290MW DH

Profile 4 150MW DH

Profile 5 0MWDH cond.

Yearly average 269 MW DH

El t i l t ffi T t l ffi

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Electrical net efficency Total efficency

Efficiency summaryy y

Efficiency penalty condensing

Efficiency summary - condensing and DH operation

90,0CondensingDH yearly condensing

operation: 8.5 %-points

Efficiency penalty67,070,0

80,0

Condensing operation

DH -yearly average

Efficiency penalty district heating operation:

8.2 %-points41,4

44,9

36 4

58,8

40,0

50,0

60,0

c

i

e

n

c

y

[

%

]

p

Efficiency penalty lower in district heating operation

33,236,4

20,0

30,0

,

E

f

f

i

due to better possibilities for low temperature heat integration

0,0

10,0

AirCFB with DH OxyCFB with DH AirCFB condensing OxyCFB condensing

El t i l t ffi T t l ffi

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integrationElectrical net efficency Total efficency

ASU oxygen purity optimisation studyyg p y p yImpact of ASU O2 purity

CO2 avoidance cost CO2 capture cost CO2 capture rate

37,00 100

%

]

32,00

O

2

c

o

s

t

[

/

t

o

n

] 95

c

a

p

t

u

r

e

r

a

t

e

[

%

CO2 capture rate

27,00CO

90

C

O

2

c

22,0095% 97% 99,5%

Oxygen purity [%]

85

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