Tar formation during eucalyptus gasification in a bubbling fluidized bed reactor: Effect of feedstock and reactor bed composition


Tar compounds are inevitably present in the raw producer gas from biomass gasification and currently represent the main barrier for the commercial breakthrough of gasification technologies. In the present work, tar concentration in the producer gas from direct gasification of distinct types of residual forest biomass from eucalyptus in a 5 kWth bubbling fluidized bed reactor was investigated. The influence of the feedstock chemical composition and gasifier operation time was evaluated. Average tar concentration values in the raw producer gas were between 1.5 and 13.3 g/Nm(3), representing a tar production between 8.4 and 67.0 g tar/kg biomass db, which surpasses suggested tar concentration limits for various potential applications for the producer gas. Major average tar compounds present in the tar sampled from the raw producer gas were benzene (47.1 %wt), toluene (21.6 %wt), naphthalene (10 %wt) and indene (6.4 %wt). A significant decay of the tar concentration in the producer gas was observed with increasing gasifier operation time, namely up to 50% within 45 min of operation, indicating its dependency on inorganics (e.g., CaCO3, KCl, maximum 5.5 %wt) and solid carbon (maximum 22.7 %wt) accumulation in the reactor bed.



subject category

Thermodynamics; Energy & Fuels; Mechanics


Pio, DT; Ruivo, LCM; Tarelho, LAC; Frade, JR; Kantarelis, E; Engvall, K

our authors


The authors acknowledge the financial support provided through the project NOTARGAS -Novel catalyst concepts for tar-free oxy-steam gasification of biomass (ref. POCI-01-0145-FEDER-030661) and project SusPhotoSolutions -Solucoes Fotovoltaicas Sustentaveis, PO Centro 2020 (ref. CENTRO-01-0145-FEDER-000005). Thanks are due to Portuguese Foundation for Science and Technology (FCT)/Ministry of Science, Technology and Higher Education (MCTES) for the financial support to CESAM (UIDP/50017/2020 + UIDB/50017/2020) and CICECO (UIDB/50011/2020 & UIDP/50011/2020), through national funds and Compete 2020, and to BRISK 2 funded by EU Horizon 2020. The authors also acknowledge the FCT and The Navigator Company for providing financial support to the PhD scholarship granted to Daniel Pio (ref. PD/BDE/128620/2017). Thanks are extended to FCT for providing the financial support to the PhD scholarship granted to Luis Ruivo (ref. SFRH/BD/129901/2017). Part of this work was carried out within the Swedish Gasification Centre (SFC) consortium. Funding from the Swedish Energy Agency (34721-2), academic and industrial partners is gratefully acknowledged.

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