Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
Fluidization of mixtures of sand and wood bark biomass particles – an experimental study
Submission Author:
Flavia Zinani , RS , Brazil
Co-Authors:
Guilherme A Genehr, Flavia Zinani, Maria Luiza Sperb Indrusiak
Presenter: Guilherme A Genehr
doi://10.26678/ABCM.ENCIT2016.CIT2016-0265
Abstract
Fluidized beds are extensively employed in thermal energy conversion industries. One of the main applications is the combustion of solid particulate fuels in fluidized beds of sand or limestone. Fluidized beds are a good choice to burn low rank coals, biomass and fuels of high humidity, such as industrial and urban waste. The fluid dynamics of a fluidized bed provides valuable information for the design and operation of such a system. The objective of this work was to determine physical characteristics of biomass consisting of pinus (Pinus elliottii) and Eucaliptus (Eucalyptus) bark particles, and to investigate the fluid dynamic behavior of binary mixtures of biomass and sand. The characteristic velocities (initial fluidization, apparent fluidization and complete fluidizadion velocity) and fluidization curves of biomass-sand mixtures were analyzed. The experiments were performed in a lab scale fluidized bed with internal diameter of 94 mm and 1.2 m in height. The fluidization agent was air at room temperature. The average particle sizes were of 579.13 um for pinus and 537 um for eucalyptus, and densities of 1,271 kg/m³ and 1,386 kg/m³, respectively. The biomass-sand mixtures were made in proportions of 1.43% to 41.89% biomass/sand (m/m). The effects on fluid dynamics of the nature of each biomass and the mass fraction of biomass contained in the mixture were investigated. The results showed that with the increase of biomass proportion, characteristic velocities tend to increase, being most significant for Eucalyptus, which also showed higher tendency to segregation. The comparison with predictions of empirical correlations for complete fluidization velocities showed that correlations developed for other types of biomass-inert mixtures may lead to large discrepancies, up to 30%, when applied to wood bark biomass, as in this work.
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