C CH HE E MI IC CA AL L E EN N GI IN NE EE ER RI IN N G T TR RA AN NS SA AC CT TI I ON NS S VOL. 37, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Eliseo Ranzi, Katharina Kohse- HöinghausCopyright © 2014, AIDIC Servizi S.r.l., ISBN 978-88-95608-28-0; ISSN 2283-9216 Characterization of Ashes from Different Wood Parts of Norway Spruce Tree Liang Wang* a , Janka Dibdiakova b a SINTEF Energy Research, Sem Sælands vei 11, Trondheim, Norway b Norwegian Forest and Landscape Institute, NO-1431, Ås, Norway liang.wang@sintef.no Woody biomass from the forest sector is an abundant resource for renewable energy generation. Conventional woody biomass materials such as timber and stem are normally high quality solid fuels for combustion applications in terms of ash related operational problems. Recently, new raw woody materials such as forest residue are gaining interests for energy production purpose. Forest residue is the remaining fraction after harvest and outtake of the wood timber, including tree tops, branches and barks. Compared to conventional woody biomass, the forest residue has a wide variation of ash content and concentration of ash forming matters. The aim of this work was to characterize and investigate different parts from Norway spruce trees regarding ash content, ash composition and ash melting and slagging behaviors. Different parts from spruce tree were studied in present work including stem wood, bark, branch and twigs. The ash content and ash melting temperature of the four fuel samples were measured through following standard procedures. Concentrations of main ash forming elements were analyzed by an inductively coupled plasma optical emission spectroscopy (ICP-OES). The ashes from stem wood, bark and twigs were further investigated by a scanning electron microscopy equipped with energy dispersive X-Ray analysis (SEM-EDX) and X-Ray diffractometry (XRD). The results showed that the branches and twigs contain higher contents of ash forming matters than that of the stem wood. Chemical compositions of ashes from four parts of the spruce tree are dominated by Ca, K, and Si. The K and Na contents in the branches and twigs are significantly higher than that of stem wood and bark, indicating high tendency of ash melting and slagging. The melting points of ashes from branch and twigs were 100-200 °C lower than those of the ashes from stem wood and bark, respectively. SEM-EDX and XRD analysis, melting of ashes from branch and twigs are mainly attributed to formation and fusion of low temperature melting alkali silicates. 1. Introduction Utilization of woody biomass for heat and power production has been mainly restricted to timber, sawdust, wood chips and shavings from sawmills and wood working industry (Boström et al., 2011). However, with the rapid increase of demand of bioenergy, woody biomass materials from forest residues are gaining continuous interests recently. Forest residues are derived from harvest of forests and outtake of timber process. In Norway, 37% of the Norwegian mainland is covered by forest (119,000 Km 2 ). About 1.5 million m 3 are produced annually in Norway with large amounts available for energy production. Norway has set a goal to produce new 14 TWh bioenergy by 2020, and extend use of forest residues will certainly help to meet the goal (Liang et al., 2013). With development of collecting and bundling technologies, the efficient recovery and utilization of the forest residues become more important. Currently, combustion is still the most widely used technology for converting woody biomass into heat and power (Liang et al., 2013). However, as a group of solid fuel for combustion applications, in contrast to ordinary woody biomasses, the forest residues have large variations in total fuel ash content and composition of ash forming elements (Werkelin et al., 2005). Therefore, the ash transformation chemistry during combustion of forest residues may be considerably different than those of conventional woody biomass fuels (Ehsan et al., 2013). In previous studies, ashes in pure sample of stem wood, bark and foliage from trees of pine, spruce, birch DOI: 10.3303/CET1437007 Please cite this article as: Wang L., Dibdiakova J., 2014, Characterization of ashes from different wood parts of norway spruce tree, Chemical Engineering Transactions, 37, 37-42 DOI: 10.3303/CET143700737
