Fast Pyrolysis and Bio-Oil Upgrading

1 Fast Pyrolysis and Bio-Oil UpgradingRobert C. BrownIowa State UniversityandJennifer HolmgrenUOPFast Pyrolysis Rapid thermal decomposition of organic compounds in the absence of oxygen to produce liquids, char, and gas Dry feedstock: <10% Small particles: <3 mm Short residence times: -2 s Moderate temperatures (400-500 oC) Rapid quenching at the end of the process Typical yieldsOil: 60 -70%Char: 12 -15%Gas: 13 -25%Source: Piskorz, J., et al. In Pyrolysis Oils from Biomass, Soltes, E. J., Milne, T. A., Eds., ACS Symposium Series 376, SprucePoplarMoisture content, wt% size, m (max)1000590 Temperature500497 Apparent residence Yields, wt %, composition, wt %, Total liquid ( Bio-Oil ) from flash Pyrolysis is a low viscosity, dark-brown fluid with up to 15 to 20% waterMultiple reaction pathways for Pyrolysis of celluloseCelluloseFastSlowAlkali-catalyz eddehydrationChar + waterLevoglucosanHydroxyacetaldehydeDepo lymerizationFast Pyrolysis Advantages Operates at atmospheric pressure and modest temperatures (450 C)

2 Yields of Bio-Oil can exceed 70 wt-% Disadvantages High oxygen and water content of Pyrolysis liquids makes them inferior to conventional hydrocarbon fuels Phase-separation and polymerization of the liquids and corrosion of containers make storage of these liquids difficultSeveral Kinds of Fast Pyrolysis Reactors Bubbling fluidized bed Circulating fluidized beds/transport reactor Rotating cone pyrolyzer Ablative pyrolyzer Vacuum Pyrolysis Auger reactorBubbling Fluidized BedGas, Char, and Oil Vapors and AerosolFreeboardFluid bedFluidizing gasBiomassFeederDistributorplateHeat Heat supplied externally to bed Good mass & heat transfer Requires small biomass particles (2-3 mm)

3 Circulating Fluidized Bed/Transport ReactorGas and Oil Vapors and AerosolFluidizing gasBiomassFeederDistributorplateAirFlue GasPyrolyzerCombustorSand & charHot Sand Hot sand circulated between combustor and pyrolyzer Heat supplied from burning char High throughputs but more char attritionRotating Cone PyrolyzerHot SandBiomassVapors and AerosolRotation Sand and biomass brought into contact within rotating cone Compact design and does not need carrier gas Requires very small biomass particles and is hard to scale-upAblative Pyrolyzer High pressure of particle on hot reactor wall achieved by centrifugal or mechanical motion Can use large particles and does not require carrier gas Complex and does not scale wellSpinning DiskPressure Applied to WoodBio-oil Liquid Released from WoodVacuum Pyrolysis Biomass moved by gravity and rotating scrappers through multiple hearth pyrolyzer with temperature increasing from 200 C to 400 C Can use larger particles and employs little carrier gas Expensive vacuum pump and difficult to scale-upScrapper DriverBiomassCharVacuum pumpMultiple hearth vacuum Pyrolysis reactorCondensersAuger ReactorBiomassAuger driverChar & sandVapors & aerosol to condenserHot sandAuger reactor Hot sand and biomass mixed

4 By auger Suitable for small scale Requires hot sand heating and circulation systemRelative Merits of Various ReactorsPropertyStatusBio-oilwt%Comp-lex ityFeed sizeInert gas needSpecific sizeScaleupFluid bedDemo75 MediumSmallHighMediumEasyCFBP ilot75 HighMediumHighLargeEasyEntrained None65 HighSmallHighLargeEasyRotating conePilot65 HighV smallLowSmallHardAblativeLab75 HighLargeLowSmallHardAugerLab65 LowSmallLowMediumEasyVacuumDemo60 HighLargeLowLargeHardThe darker the cell color, the less desirable the : 1 20 kg h-1 Pilot: 20 200 kg h-1 Demo: 200 2000 kg h-1 Adapted from PYNE IEA Bioenergy will dominate?TECHNOLOGY STRENGTHS trongAverageWeakAblativeCyclonicRotating coneEntrained flowFluid bedCirculating fluid bedand transport reactorAugerMARKET ATTRACTIVENESSHighLowAdapted from PYNE IEA Bioenergy Pyrolysis SystemMillAirQuencherBio-oilBio-oilstora geHopperFluidizing gasFlue gasVapor, gas, char productsCycloneCombustorPyrolysis gasesLignocellulosicfeedstockPyrolysisre actorCharFeederMotorScale$0$1,000$2,000$ 3,000$4,000$5,000$6,000$7,000$8, Input (million US tons/yr)Capital Cost (million 2005 US dollars) 050100150200250 Diesel Output (million US gallons/yr)Small gasification (multiple units 110,000US ton/yr)

5 + small FT multiple unitsSmall Pyrolysis (multiple units 110,000US ton/yr) + large FTLarge gasification + large FT$400,000 pbpd$100,000 pbpdAdapted from: Bridgwater, ACS Meeting, Washington, , 2005 Suitable Feedstocks Wide variety of feedstocks can be used Fibrous biomass usually employed Wood higher yielding than herbaceous biomassStorage & Transportation Distributed preprocessing allows transport and storage as liquid High acidity requires storage in stainless steel or plastic Stability problems need to be solvedPost Processing to Motor Fuels Direct application of Bio-Oil Hydrocrackingof Bio-Oil Gasification of Bio-Oil Fermentation of Bio-oilBio-Oil Burned in Diesel Engines Bio-Oil used as directly as diesel fuel substitute Only suitable for stationary power applicationsPyrolyzerBio-Oil RecoveryBio-Oil

6 StorageStationary Diesel EngineFibrous biomassBio-oil vaporCycloneBio-OilCharBio-Oil Hydrocracking Directly converts biomass into liquid Bio-Oil (lignin, carbohydrate derivatives, and water) and char Bio-Oil catalytically converted into hydrocarbon fuel (green diesel)PyrolyzerCarbohydrate derived aqueous phaseBio-Oil RecoveryPhase SeparationSteam ReformerHydrocrackerFibrous biomassBio-oil vaporHydrogenGreen dieselCycloneLigninCharBio-Oil Gasification Bio-Oil and char slurried together to recover 90% of the original biomass energy Slurry transported to central processing site where it is gasified in an entrained flow gasifier to syngas Syngas is catalytic processed into green diesel (F-T liquids)

7 PyrolyzerBio-Oil RecoverySlurry PreparationPumpEntrained Flow GasifierFibrous biomassBio-oil vaporSlagCycloneBio-OilCharFischer Tropsch ReactorGreen DieselBio-Oil FermentationFermenterFiberPyrolyzerAnhyd rosugar& other carbohydrateBio-Oil RecoveryPhase SeparationDetoxificationLigninHot water extractionPentoseFiber byproductBio-oil vaporFermenterDistillationWaterEthanolCy cloneCharEnergy Efficiency Conversion to 75 wt-% Bio-Oil translates to energy efficiency of 70% If carbon used for energy source (process heat or slurriedwith liquid) then efficiency approaches 94%Source: Gas (CO, H2, light hydrocarbons) Can be used to heat Pyrolysis reactor Char: Several potential applications Process heat Activated carbon Soil amendmentPotential Co-Products from Bio-OilProducts of Pyrolysis for several different pretreatments of cornstover (Brown et al.)

8 2001)No PretreatmentAcid HydrolysisAcid WashAcid Wash with catalystProducts (Wt% maf) (Wt %) Assurance Bio-Oil quality issues: Moisture content Particulate content Sulfur and nitrogen content StabilityEquipment Maintenance Potential problems with Pyrolysis equipment Bed agglomeration Clogging of condensers ESP performance Catalytic reactors Poisoning by sulfur and chlorine CokingWaste Streams Main products (gas, char, Bio-Oil ) account for all mass of biomass feedstockTechnical Barriers Preparing dry, finely divided biomass particles Maintaining high Bio-Oil yields Improving Bio-Oil stability Determining optimal scale of facilityAlternative Fuels: TargetsAlternative Fuels: Targets Alternative fuels may need to target.

9 Alternative fuels may need to target: < 100 gm CO< 100 gm CO22/km WTW /km WTW GTL, DME from gas GTL, DME from gas close, but close, but not there yetnot there yet Several other alternatives in study Several other alternatives in study (not shown for simplicity)(not shown for simplicity) Engine manufacturers developing Engine manufacturers developing more efficient advanced more efficient advanced ICEICE ssin in addition to hybrids and FCaddition to hybrids and FC ss Variable DI gasolineVariable DI gasoline Part HomogeneousPart Homogeneous diesel diesel combustioncombustion Combined CombustionCombined Combustion systemssystems Improve fuel efficiencyImprove fuel efficiencySource: CONCAWE / EU CAR / Source.

10 CONCAWE / EU CAR / EU EU CommComm nn, , DecDec20032003 WTW Energy /GHG Emissions Clusters WTW Energy /GHG Emissions Clusters 0050501001001501502002002502503003003503 5040040000200200400400600600800800100010 00 Energy, MJ/kmEnergy, MJ/kmGHG, COGHG, CO22 Equivalent, gm/kmEquivalent, gm/kmHydrogenHydrogenfrom coal, FCfrom coal, FCDME from NGDME from NGFAMEFAMEC onventional Conventional EtOHEtOHHydrogen fromHydrogen frombio, ICEbio, ICEG asoline & DieselGasoline & DieselGTL from NGGTL from NGGreen DieselGreen DieselGasoline & Diesel in Advanced Gasoline & Diesel in Advanced ICEICE ssSet Tough Targets!Set Tough Targets!Biorenewables and Petroleum Biorenewables and Petroleum Feeds: Relative AvailabilityFeeds.