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/Nm3, 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 headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Keyword

Ash

Biomass

Bubbling fluidized bed

Eucalyptus

Gasification

Tars

Publication and Content Type

ref (subject category)

art (subject category)