Pyrolysis of sawdust into medium-grade fuels and chemical preservatives

The importance of energy for the development and social growth of a nation cannot be over-emphasized. However, there is energy shortage world-wide and there is the need to shift attention from fossil fuels to biomass energy due to their negative effect on the environment. This work examined the thermo-chemical conversion of sawdust into medium- grade fuel products and chemical preservatives.

A pyrolysis chain that consists of brick furnace, condensate receiver, retort and gas collection unit was developed and used for the experiment. The moisture content of sawdust was determined, while the weight of pieces of wood used for pyrolysis was measured and recorded. Oven dried sawdust was loaded into the retort and placed inside the furnace chamber. The sawdust in the retort was heated up. The process took about 30 minutes. The products of the pyrolysis obtained were weighed and expressed in percentage of the oven-dried weight of feedstock. The pyrolytic gas was further analyzed and its constituents were determined using empirical/molecular formula.

The results showed that the products of pyrolysis were 17% char, 41% mixture of pyrolytic oil/pyroligneous acid and 42% of pyrolytic gas. The pyrolytic gas was found to contain 74.69% of carbon, 25.31% of hydrogen. The results of analysis showed that the constituent gases present in the pyrolytic gas expressed in percentage as 33% of methane (CH₄), 62.5% of ethane (C₂H₆) and 42% of hydrogen gas (H₂). The higher heating value of sawdust char was calculated to be 17,100kJ/kg.

From the study, it can be concluded that, sawdust lent itself easily to process of pyrolysis and had been successfully pyrolyzed into medium-grade biomass fuels. The conversion efficiency was 89.19%.