BATCH AND CONTINUOUS PYROLYSIS OF RUBBER WOOD SAWDUST FOR PRODUCTION OF BIO-ENERGY AND BIO-CHEMICALS

The prospect of energy generation and chemical derivation based on biomass
utilization is drawing great attention. One of the promising technologies to generate
valuable fuels and chemical products from biomass is through a pyrolysis process. It
is a heating process of organic materials at a medium temperature between 400 to
800 °C under the absence of oxygen and in a short retention time. It converts biomass
into liquid (bio-oil), solid (bio-char), and gas (pyrolysis gas) products. In this research,
rubber wood sawdust (RWS) residue with a size range of 0.15 to 0.50 mm was
pyrolyzed by two methods of batch and continuous pyrolysis. The first part of the
study is to determine the influence of pyrolysis temperature (450, 500, 550, and
600 °C) by using a drop-type fixed bed pyrolyzer. When pyrolysis temperature
increased, the yield of bio-char reduced from 38.7 to 25.7 wt%, while bio-oil and noncondensable
gas (NCG) yields increased. However, at a certain high temperature
(550 °C), the bio-oil yield started to decrease because secondary reaction happened
and more gas was produced. To evaluate the effect of fluidization gas velocity, Ug
(3.64, 4.55, and 5.46 cm/s), the second part involved continuous pyrolysis of RWS via
a bubbling fluidized bed pyrolyzer. As the Ug was increased, the bio-oil yield
increased from 26.2 to 29.3 wt%, but the yield of pyrolysis gas declined from 47.6 to
42.8 wt%. Physicochemical characteristics of RWS biomass and pyrolysis products
were determined using various analyses. Bio-oils produced in this study had high
percentage of oxygen (52 to 73 wt%) and hydrogen (6 to 11 wt%) than the RWS
feedstock and char, indicating high water content (33 to 76 wt%) which considerably
decreased the calorific value (CV). By applying fractional condensation setup, water
content of bio-oil fractions was reduced. Acetic acid, phenol, cyclopentanone, and
tetrahydrofuran (THF) were the main bio-oil compounds. The bio-char product had
significantly higher carbon composition (70 to 78 wt%) and CV (26 to 30 MJ/kg)
when compared to the biomass feedstock and bio-oil product. The major components
of pyrolysis gas were CO2 (43 to 53 wt%) and CO (33 to 37 wt%).