Fluidized Bed Combustion of Biomass and Waste-derived Fuels Current Status and Challenges

Waste-To-Energy Research and Technology Council, WTERT 2005 Fall Meeting at Columbia University New York City, October 20-21, 2005 Fluidized Bed Combustion of Biomass and Waste-derived Fuels Current Status and Challenges Mikko Hupa Åbo Akademi University Turku, Finland

Åbo Akademi University Turku FINLAND

Åbo Akademi University Process Chemistry Centre - Combustion chemistry - Wood and paper making chemistry - Sensors and process analysis - Kinetics and catalysis 20 faculty and post docs 35 ongoing PhD Theses Intense collaboration with industry

Fluidized Bed Combustion of Biomass and Waste-derived Fuels Current Status and Challenges Introduction Status of the FBC technology Current research Fluidized bed gasification Conclusions

Bubbling Fluidized Bed Combustion Flue Gas + Fly Ash Fuel: Fresh, Partly Pyrolysed, Char Air Fuel Air Bed material: Quartz, Limestone; fresh, calcined, sulphated Void Space Ash

Circulating Fluidized Bed Combustion Cyclone Air Fuel Air Flue Gas + Fly Ash Fuel: Fresh, Partly Pyrolysed, Char Limestone: Fresh, Calcined, Sulphated Void Space Ash

Fluidized Bed Combustion Systems BFBC: Bubbling Fluidized Bed Boilers - fluidization velocity 1-3 m/s - reactive fuels (wood and biomasses) CFBC: Circulating Fluidized Bed Boilers - fluidization velocity 6-10 m/s - less reactive fuels (coal, oil shale, petroleum coke)

Fluidized bed boilers common features + low combustion temperature + flexible to fuel quality and variations + high combustion efficiency + low NO + easy SO2 reduction - ash components may cause bed sintering - residual ash may be difficult to dispose

Commercial status

Cumulative number 800 600 400 200 Number of FB devices worldwide (2004) CFBC BFBC PFBC FBG 0 1975 1980 1985 1990 1995 2000 Year

Cumul. capacity [MW th] 80 000 60 000 40 000 20 000 0 Capacity of FB devices worldwide (2004) CFBC BFBC PFBC FBG 1975 1980 1985 1990 1995 2000 by year

Steam drum Superheaters and reheaters Boiler tubes Fuel feed Air feed Furnace Cyclone Economizers Ash hoppers LUVO

Alholmen CFBC Jakobstad, Finland 550 MW (545 C) Peat, Bark, REF, Forest Residue, Sawdust, Coal, Oil Boiler Efficiency 92 % NO x SO 2 Particulate 50 mg/mj 100 mg/mj 30 mg/m 3 n Kvaerner Power Oy - 2001

Mälarenergi AB, Västerås 157 MWth 170 bar 540 C wood residues peat coal Foster Wheeler 2002

Capacity [MW th] 1000 800 600 400 200 Thermal Power (MWth) of the CFBCs Worldwide Capacity of CFBCs worldwide (2005) Poludniowy Koncern Energet yczny (PKE) Poland Gardanne France Robert son Texas-New Mexico Duisburg I Germany 0 1975 1980 1985 1990 1995 2000 2005 2010 Year

Boilers in by Chinese Companies Zhongyang Luo, Kefa Zen (2005) 150 MW th range: 50+ units operating 300 MW th range: 10 operating + 10 under construction 400 MW th + range: 100 units commisioned/under constr.

Cumul. capacity [MW th] 80 000 60 000 40 000 20 000 0 Capacity of FB devices worldwide (2004) CFBC BFBC PFBC FBG 1975 1980 1985 1990 1995 2000 by year

Cumul. capacity [MW th] 160 000 120 000 80 000 40 000 0 Capacity of FB devices worldwide (2004) CFBC BFBC PFBC FBG 1975 1980 1985 1990 1995 2000 by year

Cumul. capacity [MW th] 160 000 120 000 80 000 40 000 0 Capacity of FB devices worldwide (2004) China CFBC BFBC PFBC FBG CFBC in China by Chinese companies (estimate) 1975 1980 1985 1990 1995 2000 by year

Fuels

Biofuels Waste derived fuels Opportunity fuels for FBC? Forest residues Annual crops Prunings Shells, husks & hulls Olive stones RDF (refuse derived fuels) Waste sludges MBM (meat and bone meal) Chicken litter Coal Slurry Pet coke Åbo Akademi Fuel Data Bank

Emissions

Flue Gas Emission Components 100 % 0 CO 2 Carbon Dioxide 1 % CO Carbon Monoxide / C x H y Hydrocarbons 100 ppm -5 SO 2 Sulfur Dioxide / NO x Nitrgen Oxides 1 ppm PAH Polyaromatic Hydrocarbons 1 ppb (µg/kg) -10 As, Cr, Ni, V, Pb, Cd, Hg,... Heavy Metals 1 ng/kg Dioxins, Furans 1 pg/kg -15

EU Directive on Incineration of Waste Containing Fuels Acidic Gases HCl 10 mg/m 3 n (on-line) HF 1.0 mg/m 3 n (on-line) SO 2 50 mg/m 3 n (on-line) NO x 200 mg/m 3 n (on-line) Dust 10 mg/m3n (on-line) Metals, EDD Hg 0.05 mg/m3n (twice a year) Cd+Tl 0.05 mg/m3n (twice a year) Sb+As+Co+Cr+ Cu+Pb+Mn+Ni+V 0.5 mg/m3n (twice a year) (0.05 mg/m3n in flue gases 0,4 mg/kg dry fuel) Dioxins and furans 0.1 ng/m 3 n (measurement twice a year)

Recovered Wood Fuel Metal Contents (ppmw = mg metal/kg fuel) heavy metals 350.00 ppmw corrected value 300 300.00 250.00 Rest fraction, analysed Leached in HCl Leached in Acetate Leached in H2O Untreated Fuel 200 mg/kg fuel 200.00 150.00 100 100.00 50.00 0 0.00 As Cd Co Cr Cu Hg Mn Ni Pb Sb Tl V Zn As Cd Co Cr Cu Hg Mn Ni Pb Sb Tl V Zn

Fouling and corrosion

BFBC for Biomass Fuels Rice husk Eucalyptus bark

700 Steam temperature for BFBCs worldwide (2005) Temperature [ C] 600 500 400 300 200 100 1975 1980 1985 1990 1995 2000 2005 2010 Year

Ash Elements in Spruce Tissues (J. Werkelin 2005)

Five Spruce Tissues Wood Bark Twigs Needles Shoots

Ash Elements in Spruce Tissues (J. Werkelin 2005)

Corrosion Test by Alkali Salts Before heat treatment After heat treatment Prepared for SEM

Corosion Analysis by SEM

Corrosion due to Alkali Salts Steel: A Time: 168 h (Skrifvars et al. 2005) 140 Corrosion layer thickness m 120 100 80 60 40 20 0 Salt 10 Salt 9 Salt 8 Salt 7 Salt 6 450 C Salt 5 500 C525 C Salt 0 550 C 575 C600 C

Corrosion due to Alkali Salts Steel: B Time: 168 h (Skrifvars et al. 2005) Corrosion layer thikcness m 100 90 80 70 60 50 40 30 20 10 0 450 C 500 C525 C550 C 575 C 600 C Salt 10 Salt 9 Salt 8 Salt 7 Salt 6 Salt 5 Salt 0

Corrosion due to Alkali Salts Steel: C Time: 168 h Corrosion layer thickness μm 100 90 80 70 60 50 40 30 20 10 0 450 C 500 C 525 C550 C 575 C 600 C Salt 10 Salt 9 Salt 8 Salt 7 Salt 6 Salt 5 Salt 0 (Skrifvars et al. 2005)

Gasification

CFB Gasifier REACTOR UNIFLOW CYCLONE 850 C GASIFICATION AIR FAN FUEL FEED 900 C RETURN LEG AIR PREHEATER COOLING WATER HOT LOW CALORIFIC GAS (750-650 C) Foster Wheeler BOTTOM ASH COOLING SCREW WTERT 2005 Fall Meeting at Columbia BOTTOM University, ASH October 20, 2005

BIOMASS GASIFICATION - COAL BOILER - LAHTI PROJECT 350 MW 540 蚓 /170 bar Biomass 300 GWh/a -15 % fuel input CO 2 Reduction - 10 % Processing 50 MW Pulverized coal flames Power * 600 GWh/a District Heat * 1000 GWh/a Gasifier Gas flame Bottom ash Coal Natural Gas 1050 GWh/a -50 % 650 GWh/a -35 % Fly ash Foster Wheeler

Conclusions (i) FBC rapidly expanding now especially in China CFBC - upto 1000 MWth - novel cyclones and superheaters BFBC - interesting for reactive fuels

Conclusions (ii) PFBC well demonstrated in 800 MWth class FB gasifiers promising for producing gas to cofiring

Conclusions (iii) Waste derived fuels great potential for FBC Challenge to boiler manufacturers & operators: Emission control (heavy metals) Bed sintering and fouling control Corrosion control Multifuel firing and fuel interaction

Aknowledgements B. Leckner, L-E. Åmand (Chalmers), H. Tran (Toronto) C. Mueller, R. Backman, B-J. Skrifvars, M. Zevenhoven, P. Yrjas, S. Kallio, P. Kilpinen, J. Konttinen, M. Theis, J. Werkelin (Åbo) Kvaerner Power, Foster-Wheeler, Vattenfall, Metsä-Botnia, Andritz, International Paper Tekes, Academy of Finland