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Some Chemical Compositional Changes in Miscanthus and White Oak Sawdust Samples during Torrefaction
Idaho National Laboratory, Energy Systems and Technologies Directorate, Biofuels and Renewable Energies Department, P.O. Box 1625, Idaho Falls, ID 83415-2025, USA
* Author to whom correspondence should be addressed.
Received: 13 July 2012; Accepted: 19 September 2012 / Published: 16 October 2012
Abstract: Torrefaction tests on miscanthus and white oak sawdust were conducted in a bubbling sand bed reactor to see the effect of temperature and residence time on the chemical composition. Process conditions for miscanthus and white oak sawdust were 250–350 °C for 30–120 min and 220–270 °C for 30 min, respectively. Torrefaction of miscanthus at 250 °C and a residence time of 30 min resulted in a significant decrease in moisture—about 82.68%—but the other components—hydrogen, nitrogen, sulfur, and volatiles—changed only marginally. Increasing torrefaction temperatures to 350 °C with a residence time of 120 min further reduced the moisture content to 0.54%, with a significant decrease in the hydrogen, nitrogen, and volatiles by 58.29%, 14.28%, and 70.45%, respectively. Regression equations developed for the moisture, hydrogen, nitrogen, and volatile content of the samples with respect to torrefaction temperature and time have adequately described the changes in chemical composition based on R2 values of >0.82. Surface plots based on the regression equation indicate that torrefaction temperatures of 280–350 °C with residence times of 30–120 min can help reduce moisture, nitrogen, and volatile content from 1.13% to 0.6%, 0.27% to 0.23%, and 79% to 23%, with respect to initial values. Trends of chemical compositional changes in white oak sawdust are similar to miscanthus. Torrefaction temperatures of 270 °C and a 30 min residence time reduced the moisture, volatiles, hydrogen, and nitrogen content by about 79%, 17.88%, 20%, and 5.88%, respectively, whereas the carbon content increased by about 3.5%.
Keywords: miscanthus; white oak sawdust; torrefaction; temperature; time; chemical composition
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Tumuluru, J.S.; Boardman, R.D.; Wright, C.T.; Hess, J.R. Some Chemical Compositional Changes in Miscanthus and White Oak Sawdust Samples during Torrefaction. Energies 2012, 5, 3928-3947.
Tumuluru JS, Boardman RD, Wright CT, Hess JR. Some Chemical Compositional Changes in Miscanthus and White Oak Sawdust Samples during Torrefaction. Energies. 2012; 5(10):3928-3947.
Tumuluru, Jaya S.; Boardman, Richard D.; Wright, Christopher T.; Hess, J. R. 2012. "Some Chemical Compositional Changes in Miscanthus and White Oak Sawdust Samples during Torrefaction." Energies 5, no. 10: 3928-3947.