AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Chemical Composition Analysis of Wood Pellets
MOHAMMED RAHMAN, Philip K. Hopke, Lisa Rector, George Allen, Clarkson University
Abstract Number: 34 Working Group: Combustion
Abstract Wood now ranks nationally as the third most common heating fuel after gas and electricity. The most convenient form of wood is pellets. However, the combustion of wood pellets produces atmospheric pollution. Several voluntary standards have been established for wood pellets including ENplus, CANplus, and PFI. As part of the consideration for the development of a regional standard, wood pellet samples manufactured in the United States were analyzed for their energy, ash, moisture, and chemical composition. The pellet samples from different manufacturers were obtained from various locations in New England and New York. Calorific value, moisture and ash content of the samples were determined according to the American Society for Testing and Materials (ASTM) methods, sulfate and chloride samples were prepared using ASTM methods and analyzed by ion chromatography (IC). The elemental compositions of the wood pellet samples were determined using inductively coupled plasma mass spectrometry (ICP-MS) following sample preparation. Samples were prepared using two different methods, direct digestion and digestion of ash, and the results compared. The results varied between the two sample preparation methods within ~5% in elemental concentrations. Mercury was measured by direct analysis of wood samples. The distributions of the sample characteristics, such as heating value (7917-8542 BTU/lb), ash content (0.27-0.76%), moisture content (2.60-8.25%), ions (sulfate: 236-595 mg/Kg; chloride: 199-690 mg/Kg) and heavy elements (As: 0.01-0.20; Cr: 0.18-0.77; Cd: 0.02-0.05; Pb: 0.05-0.89; and Hg: 0.001-0.003 mg/Kg) were measured. Most of the commercially available wood pellets in this study would meet German and European standards for elemental content. These results will help in the development of regional wood pellet standards that would reduce environmental problems related to air emissions and ash disposal and use as fertilizers for agriculture soils.