Upgradation of The Energy Content of Rice Husk Through Chemical Treated Torrefaction
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Date
2018-07
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Publisher
AAU
Abstract
Despite all its advantages biomass has some shortcomings that often create difficulties in its
wide scale use as an energy source. Compared to the other fuels like coal, biomass has a higher
oxygen content, lower calorific value, lower energy density, lower bulk density, higher
hygroscopic nature, and higher moisture content. Thus, biomass faces some technical challenges
in the energy conversion systems. Torrefaction process is the partial pyrolysis of biomass carried
out under atmospheric pressure in a narrow temperature range of 200
º
C to 300
iv
º
C, under an inert
environment which yields higher solid yield than the pyrolysis. Torrefaction of biomass
significantly changes its physical and chemical properties like moisture content, density,
grinding ability, pelletability, hydrophobicity, Calorific value, proximate and ultimate
composition, and storage. The objective of this study is to examine the torrefaction process of
lignocelluloses biomass the rice husk produced in Ethiopia by chemical treated torrefaction
process. Three torrefaction temperatures 200ºC, 250ºC and 300ºC, three holding times 20, 40
and 60min and three acid concentrations 0.75, 1.50 and 2.25g/l will be considered from the
literature value 0.25 -2.5% concentration of sulfuric acid. Design-Expert 7.0.0 three-level-threefactor
BBD was applied for experimental design and statistical analysis of results. The result
showed a significant net reduction of the volatile matter content, mass yield, moisture content,
bulk density and atomic oxygen content with the increasing torrefaction temperature and
reaction time, the atomic carbon content, higher heating value, fixed carbon content and energy
density were found to increase with higher torrefaction temperatures and time in both dry and
chemical treatment . Torrefaction temperature and holding time had a significant effect on
torrefaction process of the rice husk. From the thermo gravimetric analysis, torrefaction peaks
were observed at temperatures between 200ºC-300ºC.The FTIR shows peaks appearance of a
result of the degradation of the rice husk functional group. Therefore, the torrefied biomass
becomes is found to lie a significant fuel sources which has the potential to replace the fossil
fuel. The chemical treated torrefaction yields better result and increase the energy density.
Description
Keywords
dry, calorific value, pyrolysis, torrefaction