Mikko Hupa Åbo Akademi Turku, Finland

Åbo Akademi Chemical Engineering Department Course The Forest based Biorefinery Chemical and Engineering Challenges and Opportunities May 3-7, 2010 Thermal conversion of biomass Mikko Hupa Åbo Akademi Turku, Finland

Thermal conversion of biomass -Outline 1. Introduction 2. Combustion and biomass fuel properties p 3. Gasification to produce combustible gas 4. Gasification to produce synthesis gas 5. Pyrolysis to produce bio-oil 6. Black liquor: recovery boiler or gasifier? 7. Summary

Use of Wood in Finland (VTT 2000)

Kraft Pulp Mill pulping chemicals paper pulp stemwood chipping chips pulping round wood debarking black liquor forest harvesting bark pulping chemicals com- bustion heat & power emissions ash

Kraft Pulp Mill & Biorefinery pulping chemicals paper pulp stemwood chipping chips pulping forest round wood harvesting debarking bark extraction P knots extraction extraction P P black liquor separation P P residues heat & power recycling pulping chemicals com- bustion ---- gasifica- tion emissions synthesis gas ash biofuels (l) () synthesis P

Conversion Routes for Cellulosic Biomasses Heat & Power SynGas (CO 2 +H 2 ) Combustion Fischer-Tropsch Methanol Heat & Power Alkanes Methanol, DME Water-Gas Shift Hydrogen Cellulosic Biomass Pyrolysis etc. Bio-oilsoils Dehydroxygenation Zeolite Upgrading Liquid Fuels Fermentation Ethanol Aqueous Sugars Dehydration Aq.-Phase Processing Aromatic Hydrocarbons Liq. Alkanes or H 2 Lignin Lignin Upgrading Etherified Gasoline

N 2 Vent. O 2 CO 2 pump pump SO 2 CO/CO 2 Filter NO Vent. Single Particle Burning System (Source: Åbo Akademi)

Single Particle Burning of Wood 92.6 mg 800 ºC 21 % O 2 (air)

Fuel Particle Burning Stages H 2 O CO, CO 2, H 2 O Combustion of a solid fuel Solid fuel Air Drying O 2 CO, CO 2 C x H y O 2 Pyrolysis/ devolatilisation and gas combustion Char combustion Ah Ash

4 % Single Particle Burning On-line CO2 Analysis CO 2 fo ormation 3% 2 % 1 % 0 % 0 20 40 60 0 20 40 60 time (seconds)

Single Particle Burning Volatile Carbon vs. Char Carbon pm) Volatile carbon CO 2 (p Char carbon time

Bubbling Fluidized Bed Boiler (Metso Power) E.ON UK Steven s Croft Power Station Lockerbie UK Steam 126 MW th 48 kg/s 137 bar 537 C Fuels Wood chips, sawdust, bark, recycled wood Start-up 2007

Bubbling Fuidzed Bed Boiler (Metso Power) Secondary superheater Tertiary superheater Primary superheater Fuel silos Economizers Furnace Air preheaters Fluidized bed Hydro Beam floor

Bubbling Fluidized Bed Furnace Boiler furnace Load burners Fluidized bed Hydro Beam Floor Overfire air Fuel feeding Primary air Removal of coarse material

Use of Wood in Finland (VTT 2000)

Five Spruce Tissues Wood Bark Twigs Needles Shoots

Ash Elements in Spruce Tissues Ash Elements in Spruce Tissues (J. Werkelin 2005)

Fouling and Corrosion due to Unsuitable Fuel Mixture

Summary 1: Biomass Combustion for Heat & Power Dominating biomass-to-energy technology Finland strong with FBC technology Research on demanding feedstocks: moisture, heating value, ash, emissions Research on improved power production controlling superheater corrosion

What Happens in a Gasifier? Moisture Volatiles, tars H 2, CO Drying Pyrolysis Char gasification Droplet Solids Char Ash CO 2, H 2 O

What Happens in a Gasifier? Product gas / Syn Gas Moisture Volatiles, tars H 2, CO Drying Pyrolysis Char gasification Droplet Solids Char Ash CO 2, H 2 O

CFB Gasifier REACTOR UNIFLOW CYCLONE Foster Wheeler 850 C GASIFICATION AIR FAN FUEL FEED 900 C RETURN LEG AIR PREHEATER COOLING WATER HOT LOW CALORIFIC GAS (750-650 C) BOTTOM ASH COOLING SCREW BOTTOM ASH

BIOMASS GASIFICATION - COAL BOILER - LAHTI PROJECT 350 MW 540 C/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 Coal 1050 GWh/a -50 % Natural Gas 650 GWh/a -35 % ash Fly ash Foster Wheeler

Summary 2: Biomass Gasification & Combustion of the Gas for Heat & Power Simple process de facto partial oxidation of the fuel into a combustible gas mixture (air ratio 30-40 %) Used instead of direct combustion in special applications: lime kilns, co-firing i with coal Challenges to achieve complete conversion of the biomass fuel

Biodiesel Production in Pulp Mill Paper & pulp p Process steam & power power plant Pulp and paper mill Energy to drying Gasification and gas treatment fuel gas + steam Wood, straw energy crops, peat, RDF Biomass handling and drying bark, forest residues, other biomass steam & oxygen synthesis -gas FT-synthesis & upgrading WoodDiesel

Pressurized Gasifier for Syngas Production (VTT)

Stora Enso Neste BTL Gasification Projet UCG Long term demonstration Commercial scale R&D programme in atmospheric conditions 200-300 MWth pressurized 2004-2007 2009 => unit in operation

Biomass Gasifier for Biodiesel Demo by Stora Enso Neste in Varkaus,,Finland

Summary 3: Biomass Gasification for Synthesis gas and Liquid Biofuels Under development no plants in operation (applied for coal in South-Africa) Demanding technology: Pressurized, oxygen blown gasifier Advanced syngas cleaning Various options for synthesis: FT Diesel, Methanol, DME Very hot topic political pressure

85 m 15 m Tomlinson kattila, 1937 Wisaforest, 2005

Fray Bentos, Uruguay (Andritz)

Hainan Jinhai, Kiina (Metso 2007)

Kraft Pulp Mill Black liquor 15% solids Steam turbine Steam (power) Process steam Pulp Chips Digester Na 2 CO 3 Na 2 SO 4 CaCO 3 White liquor NaOH Na 2 S Black liquor concentration Lime kiln Causticizing i i CaO Black Liquor 75% solids Flue gas Recovery boiler Na 2 CO 3 Na 2 SO 4 Na Smelt 2 CO 3 Na 2 S Green liquor Na 2 CO 3 Na 2 S Dissolving tank Water

The Pulp Mill as a Biorefinery for Production of Transportation ti Fuels Chips Hemicellulose Digester Hemicellulose extraction Fermentation Ethanol Pulp Black liquor White liquor Gasification Syngas cleaning Syngas conversion Synthesis gas Hydrocarbons Methanol

Black Liquor Gasification for Syngas (Chemrec) Oxygen Black liquor Gasifier Gas cooler Fuel gas S-rich gas Synthesis of: - Methanol - DME - FT Hydrocarbons Quench Water Green liquor Condensate Absorber / Stripper

Summary 5: Biorefinery & Energy 1. Biomass molecules can be extracted as valuable chemicals (fractionation) 2. Biomass can be converted thermally to heat and/or power - combustion (commericial) - gasification for combustion on (commercial) 3. Residues may also be used for production of liquid biofuels: - pyrolysis for bio-oil (under development) - gasification for synthesis (under development) 4. Need for intense ns research: The devil is in the (chemical) details