Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
Eucalyptus wood drying at different temperatures and aspect ratios
Submission Author:
Tayná Moraes , SC
Co-Authors:
Tayná Moraes, Carolina Santana Michels, Robson Leal da Silva
Presenter: Tayná Moraes
doi://10.26678/ABCM.ENCIT2018.CIT18-0345
Abstract
Eucalyptus wood is the primary raw material in the industrial processing for the production of pulp, paper, and charcoal in Brazil, requiring a reduced moisture content. Usually, the drying occurs by natural convection heat transfer (outside on the ground), but using forced convection is an appealing possibility in industries, as the availability of residual thermal energy from a variety of processes, which provides hot airflow for drying. Thus, this study aims to analyze the behavior of moisture exit in eucalyptus billets, with different aspect ratios (L/D) submitted to forced drying between 100-200°C. Methodology considered small size billets (eucalyptus wood), with geometry for three different aspect ratios (1, 2, and 3) and five drying temperatures (100°C, 125°C, 150°C, 175°C, and 200°C), with total time of residence registered after reaching moisture content stability criteria, obtained by measuring the samples mass. Drying occurred in a recirculating kiln, with intervals of 30 minutes to record the intermediate total mass of each sample, and 10 minutes of preliminary natural cooling weighed in glass desiccator, for each of the test temperatures. Additionally, the moisture content via proximate analysis (dust/sawdust wood) was obtained for comparison and benchmarking of the drying stabilization criterion, reaching 7.8-8.1%. Next, highlights from results: a) At 100°C free water removal occurs, while bound water is removed at higher temperatures; b) Water removal (free and bound) reaches higher values than moisture content from the proximate analysis (~8%); c) Drying time is lower as high the temperature, while higher weight loss occurs for longer residence times, consistent with heat and mass transfer theory; d) Aspect ratios under evaluation (AR~1-3) show small differences, reaching the same level of weight loss after 2-3h tests. Thus, a similar behavior may happen for real scale eucalyptus wood in charcoal production (AR~20).
Keywords
drying rate, Diffusivity, pretreatment, thermal process, siderurgy
