Lecture 4: Fluidised Bed Oxyfuel Boilers and CCS. Monica Lupion CO 2 Capture Programme CIUDEN

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1 Lecture 4: Fluidised Bed Oxyfuel Boilers and CCS Monica Lupion CO 2 Capture Programme CIUDEN Second APP Oxy-fuel Capacity Building Course Beijing, 15th March 2010

2 Content Introduction to OxyCFB Features of CFB Supercritical CFB OxyCFB CIUDEN and OxyCFB technology Combustion technologies Overview Comparison PC-FB Boilers Comparison CFB-BFB Boilers Historical Perspective CFB Hydrodinamics Combustion in CFB Boilers Supercritical Steam Parameters Lagisza OTU Supercritical CFB Plant Introduction Challenges Emissions in OxyCFB CIUDEN OxyCFB Boiler OXYCFB300 Project

3 Combustion technologies Fixed Bed Coal Pulverised Coal- PC Subcritical Combustion Fluidized Bed Bubbling BFBC Supercritical Pressurised Fluidized Bed Circulating CFBC Ultra- Supercritical

4 Combustion technologies SUBCRITICAL PC SUPERCRITICAL PC ULTRA SUPERCRITICAL PC SUBCRITICAL CFB Performance WOC WC WOC WC WOC WC WOC WC Efficiency (HHV) CO2 emited (g/kwh) COE % Performance and economics for air-blown PC generating technologies Basis net output: 500 MWe, 61.2% wt C, HHV=25350 kj/kg Adapted from The Future of Coal, Massachussetts Institute of Technology

5 PC / FB Boilers Characteristics Bubbling Circulating Pulverized Height of the bed (m) Superficial velocity (m/s) Excess air (%) Coal size (mm) <0.1 Combustion efficiency (%) NOx (ppm) SO2 capture in furnace (%) None Comparison of PC and FB Boilers

6 Advantages of FB Boilers

7 Heat Flux (% PC max) Advantages of FB Boilers CFB Low average heat flux: furnace tubes safer and more resilient to operational upsets Height (%Total) Lower peak heat flux, different location In PC near the most vulnerable point (water to steam) In CFB where the water is just heated

8 CFB / BFB Boilers Advantages of CFB Boilers Fuel Flexibility BFB needs to adjust heat absorption by number of tubes inmersed in the bed: LIMITED FLEXIBILITY High Combustion Efficiency Better gas-solid mixing and higher burning rate Lower NOx Emissions Staged addition of comburant In Situ Sulfur Removal Smaller Grate Area Good load-following capability Higher sulfur capture capability of CFB: larger specific area of sorbents and longer residence time Higher sugerficial gas velocity: Smaller grate area (furnace grate area 2 to 3 times smaller than BFB) High fluidizing velocity and easy control: Quick response

9 Historical Perspective of CFB First experiences with CFB CFB at Commercial scale Beginning of FB Fritz Winkler: Fluidization W Lewis & E Gilliland: CFB - 60 s. Lurgi: cement industry - 80 s. 1st CFBB: 84 MW (9MW electricity) - Ahlstrom.15 MW AirCFB Lagisza Berry and Wolsky First OxyCFB with FGR OXYCFB300

10 Historical Perspective of CFB CFB Plants by Manufacturer In the World No. of Units Total Capacity (MW) In South East Asia No. of Units Total Capacity (MW) Foster Wheeler , ,760 Alstom , ,076 About 500 CFB units around the world Over 170 CFB units in the US Over 350 CFB units in China

11 Historical Perspective of CFB Evolution of CFB Unit Capacities 600 Unit Capacity (MWe) Lagisza Pilot Plant Tri-State Oriental Chem AIR-FIRED Nova Scotia Vaskiluodon General Motors Start-Up Year Turow 1 JEA OXY-FIRED CIUDEN TDP Pilot Plant Compostilla Jamestown 2015

12 CFB Hydrodinamics Property Packed bed Fluidized bed Fast bed Pneumatic Transport Application in boilers Stoker Fired BFB CFB PC Mean particle diameter (mm) < Gas velocity (m/s) Solid-solid mixing Negligible Near perfect Near perfect Small Overall voidage Temperature gradient Large Very small Small Maybe signicant Comparison of Gas-Solid Contacting Processes

13 CFB Hydrodinamics Component Furnace (below secondary air level) Furnace (above secondary air level) Cyclone Return leg (Standpipe) Loope seal/external heat exchanger Back-pass Regime Turbulent of BFB Fast fluidized bed Swirl flow Moving packed bed BFB Pneumatic transport Flow regimes in the components of a CFB

14 Supercritical CFB Technology Steam Parameter Steam Parameter 265 bar, 535ºC/571ºC 265 bar, 583ºC/601ºC 290 bar, 603ºC/621ºC Change in boiler cost (%) Adapted from Laffont et al, PowerGen-Europe Change in Investment cost (%) Efficiency increase (%) Change in CoE (%) Reference Reference Reference Reference At Lagizsa the SC-CFB firing option was found to be 20% cheaper in capital cost and 0.3% higher in net efficiency than SC-PC

15 Supercritical CFB Technology Lagizsa OTU CFB Plant Location: Poland (PKE) 460 MWe (gross) supercritical OTU-CFB World s largest single CFB Unit World s first supercritical CFB NTP: Dec 05 Hand over: June 09 FW providing boiler island BENSON vertical OTU tech licensed by Siemens AG (GE) Integrated steam cooled solids separators INTREX TM superheaters Furnace dimensions m x 10.6m - 48 m height Fuel SH Flow SH Pressure Design Parameters Bituminous coal Plant efficiency Design Steam Parameters at 100% load 361 kg/s 275 bar SH Temperature 560 ºC RH Flow RH Pressure 306 kg/s 54.8 bar Cold RH Temperature 315 ºC Hot RH Temperature 580 ºC SO2 NOx Particulates Emission (6% O2, dry) 200 mg/nm3 200 mg/nm3 30 mg/nm3 45.3% Gross 43.3% Net

16 OxyCFB Technology CFB Oxyfuel Technically viable Challenges! Oxy-CFB

17 OxyCFB Technology The established CFB advantages also exist in oxy Fuel Flexibitily Low NOx In bed SO2 capture Efficient heat transfer and uniform heat flux Further potential CO2 capture Reduce boiler size

18 Coal and limestone OxyCFB Technology Simplified diagram

19 OxyCFB Technology Penalty from Oxycombustion Fuel input 100% CO 2 Compression 3.7% Air Separation 7.0% Output 33.4% Auxiliaries 2.4% Cooling 53.5% Adapted from Andersson, Univeristy of Chalmers

20 OxyCFB Technologies Challenges Boiler and burner development Design issues CPU Removal of impurities ASU Cost of oxygen production Demonstration in 10s of MW and large scale needed to prove design, performance and economics

21 OxyCFB Technologies Challenges Design Construct Learn Operate D C A O D C A O To 2070 COMMERCIAL MW to 2070 DEMOSTRATOR MW D C A O To 2035 D C A O DEMOSTRATOR MW PILOT 1-30 MW D C A LAB MW Year Adapted from R. S. Haszeldine Science 325, (2009). Published by AAAS

22 OxyCFB Technology Differences of Combustion in O2/CO2 compared to Air-firing Source: Near Zero CO2 Emissions in Coal Firing with Oxy-fuel Circulating Fluidized-Bed Boiler. Chem. Eng. Technol. 2009, 32, No.3,

23 Emissions of OxyCFB Boilers SO2 and Calcium utilisation (Bituminous) Emissions of air- and oxy- firing tests at VTT CFB-pilot ( kw) Adapted from A Hotta,: Oxycombustion Development by Foster Wheeler. Clean coal in the future. March. 2009

24 Emissions of OxyCFB Boilers NO Emissions (Bituminous) Emissions of air- and oxy- firing tests at VTT CFB-pilot ( kw) Adapted from A Hotta,: Oxycombustion Development by Foster Wheeler. Clean coal in the future. March. 2009

25 CIUDEN OxyCFB Boiler Dimensions (m) 21x2.7x2.4 Power (MWth) 30 max O 2 (kg/h) 8775 Flue gas recycle (kg/h) Flue gas (kg/h) Coal feed (kg/h) 5469 Limestone feed (kg/h) 720 Steam (t/h) 44.6 P(bar) / T ( C) 30 / 250

26 CIUDEN OxyCFB Boiler Flexiburn Project

27 OxyCFB300 Project Source: Foster Wheeler

28 Concluding remarks OxyCFB technically feasible and cost competitive when major reduction of CO2 emissions are required The established CFB advantages also exist in oxy Fuel Flexibitily Low NOx In bed SO2 capture Adapting an existing CFB boiler for oxy technically feasible (24-30 % O2 input) Integration of components: ASU, CPU, Combustion island Demonstration at large scale are neccesary for the implementation of the technology at fully commercial size