Published on February 27, 2014
Fast Pyrolysis of Residues to Produce Phenolic Chemicals (Project: ORF-2) Dongbing Li, Cedric Briens, Franco Berruti* (Paper in press: http://dx.doi.org/10.1016/j.fuel.2013.12.042) NSERC/FPInnovations IRC & ORF-RE Project AGM, ICFAR, Western University, London, ON. Jan 7, 2014
Autothermal Fast Pyrolysis with Fractional Condensation Introduction • Bio-oil from Fast Pyrolysis of bio-residues has great potential for the production of fuels and aromatic chemicals • Fractional Condensation provides dry bio-oil with ~1% water • Autothermal pyrolysis process would be attractive: - No need for external heating. - Simplified reactor design. - Better bio-oil quality? Research Objectives: • Develop a self-sustainable fast pyrolysis process with partial (air) oxidation, for both birch bark and Kraft lignin • Maximize bio-oil yield and quality
Experimental Setup/Conditions Hot air exit T 55 °C Electrode N2 Vapors from the pyrolysis reactor Compensating line Air 15 °C T 110 °C T Biomass Hot box 80 °C T biomass slug Carrier N2 Solenoid valve Sand bed PLC Carrier gas: N2+Air Vapor residence time: 1.7 s Reactor temperature: 500, 550 °C Biomass feeding rate: 600 g/h (Mechanical mixer needed for processing Kraft lignin only) Biomass Feeder T Cotton demister 70 °C C Cold air in C-ESP (dry bio-oil) Cooling jacket with ice water Pulse gas (N2) • • Preheate r Pinch valve To vent C N2 Air Pre-heater Mechanical Stirrer Pyrolytic Reactor Ice bath Condenser 1 (dry bio-oil) Condenser 3 (water fraction) Fractional Condensation Train Biomass: Birch Bark/Kraft lignin, 5% moisture content Heat input to the pyrolytic reactor, before (at steady state) and after biomass feeding, was calculated based on the signals from the current sensors attached to the power supply for the ceramic heaters.
Achieving Energy-Neutrality BIRCH BARK • • • Autothermal pyrolysis operation was achieved with an oxygen feed of 0.08 g per g of biomass at the reaction temperatures of 500 and 550 °C The corresponding O2 molar fraction in the carrier gas was 2.8% Lignin: 0.065 g/g biomass O2 at energy-neutrality
Effect of Partial (Air) Oxidation on Gas, Char and Dry Bio-oil Yields 20 45 (a) Bio-char Yield 500°C 550°C (b) Dry bio-oil Yield 500°C 550°C 40 Dry bio-oil yield (%) Bio-char yield (%) 15 10 5 35 22 % relative loss 31 % relative loss 30 25 Energy-neutral Energy-neutral (550 °C) (500 °C ) biomass ash content BIRCH BARK • • • 0 0.00 0.02 0.04 0.06 0.08 0.10 Oxygen feed (g/g biomass) 0.12 20 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Oxygen feed (g/g biomass) Char and bio-oil were partially combusted to give higher gas yield 22% or 31% of dry bio-oil was lost at autothermal pyrolysis conditions for the reaction temperature of 500 and 550 °C Lignin: 23% (500 °C) or 21% (550 °C) dry bio-oil loss
Effect of Partial Oxidation on Bio-oil Quality: Yield of Phenolic Chemicals BIRCH BARK Comparing autothermal pyrolysis with regular, oxygen-free fast pyrolysis, the production of 7 most abundant chemical species (GC-MS/FID): • More phenolics were produced under autothermal pyrolysis conditions • Phenolics are less susceptible to partial oxidation
(a) HHV 500 °C 550 °C Ethanol Dry bio-oil HHV (MJ/kg) 34 32 30 28 26 24 0.00 0.02 0.04 0.06 0.08 0.10 0.12 500 (b) Molecular weight/distribution 2.4 2.2 400 2.0 300 1.8 1.6 200 100 0.00 500 °C molecular weight , 550 °C, molecular weight 500 °C, dispersity 550 °C, dispersity 0.02 0.04 0.06 0.08 0.10 1.4 1.2 0.12 Oxygen feed (g/g biomass) Oxygen feed (g/g biomass) BIRCH BARK • Dry bio-oil HHV was slightly decreased from autothermal pyrolysis • GPC results showed better bio-oil quality as average MW and its dispersity were both reduced deeper pyrolysis, less heavy sugars and pyrolytic lignin in the resulting bio-oil Dispersity (-) 36 Weight-average molecular weight (g/mol) Effect of Partial Oxidation on Bio-oil Quality: HHV and Molecular Weight/Distribution
Conclusions • Autothermal pyrolysis operation of bio-residues, both birch bark sawdust and Kraft lignin (results not shown in this presentation), is possible with introduction of oxygen (air) into the pyrolysis reactor. • For birch bark: under autothermal conditions, 22 % of the dry bio-oil chemicals and 25 % of total bio-oil energy are lost at the preferred reaction temperature of 500 °C. • Partial oxidation provides better bio-oil quality: - enriched phenolics concentration - reduced amount of heavy sugars and pyrolytic lignin Future work: - Efforts on the analyses of the composition of the phenolic fractions: GC-MS-FID, ORBITRAP LC-MS - Possible applications for the phenolic fractions
Acknowledgements • NSERC/FPInnovations Industrial Research Chair (IRC) Program in Forest Biorefinery • Ontario Research Fund (ORF) from Ministry of Economic Development and Innovation
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