Fast Pyrolysis of Rubber Wood Sawdust via a Fluidized Bed Pyrolyzer: The Effect of Fluidization Gas Velocity

Abstract

Rubber wood sawdust was pyrolyzed in a fluidized bed reactor at 500 °C with nitrogen as a fluidization gas and silica sand as a fluidizing bed material. The first part of the study is to determine minimum fluidization velocity (Umf) of sand, char, and binary mixture (char and sand) based on experimental and calculation methods. The next objective is to study the effect of fluidization gas velocity (Ug) on the yield and distribution of pyrolysis products. At higher gas velocity, the yield of bio-oil increased, whereas non-condensable gas decreased. To examine physicochemical properties of pyrolysis products, the third part involves analyses of pyrolysis products based on the highest bio-oil yield occurred at Ug of 5.46 cm/s. Bio-char product had significantly higher carbon composition and calorific value than original biomass feedstock and bio-oil fractions. Fractional condensation was incorporated to condense pyrolysis vapours into six fractions of bio-oil. Bio-oil products contained high percentage of oxygen and hydrogen, signifying high water content which decreased the calorific value. However, via a fractional condensation setup, composition of water was reduced at the later part of condensers. From a GC-FID quantitative analysis, major chemical compounds in bio-oil were acetic acid and phenol.