Análise do potencial do leito de jorro como reator para pirólise da casca de coco : estudo experimental e simulação via CFD

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Barcelos, Kamilla Malverdi
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Universidade Federal do Espírito Santo
The significant increase in consumption and green coconut water industrialization in Brazil has generated a lot of residues, which extend the environmental problems if disposed an inappropriate way. In the current context of growing concerns about energy issues, the potential of this biomass as a renewable energy source is highlighted. Among the thermochemical conversion technologies of lignocellulosic materials, the pyrolysis technique has received special attention and the spouted bed has been investigated as a promising reactor for this process due to the good gas-solid contact that it provides. However, the fluid dynamics complexity at this equipment remains as the main obstacle for its use. Thus, in order to contribute to the implementation of the spouted bed as pyrolysis reactor, this paper aims to investigate the fluid dynamic behavior of coconut shell and sand mixtures through experimental studies and CFD simulation. The analysis of the data of pressure drop in the bed allowed to identify stable spouted regimes for mixtures with up to 40 mass% of coconut shell. To evaluate the effect of the mass fraction of coconut shell (10, 25 and 40%) and static bed height (6, 8, 10 cm) above the minimum spouting condition, it was performed a statistical analysis using a factorial design 32 with two central points. The influence of the total mass of particles in the bed and the porosity of the mixture above the condition of minimum spouting was observed. The segregation occurred in a subtle way for all experimental conditions and the mixture index deviated more of the ideal at the base of the equipment, with predominance of sand, denser particle, in this region. The Eulerian Granular Multiphase model was used to describe the flow of air- solid in spouted beds and it was adequate to represent qualitatively this phenomenon. However, by analyzing the minimum spouting pressure drop values, it notes that the simulated results underestimate the experimental, with a maximum relative error of - 34,26%. Based on the analysis of the stability of the bed, segregation and the volume fraction of each phase in mixture, the use of mixtures with mass fraction of coconut shell of 25% is recommended in pyrolysis tests.
Energy , Pyrolysis , Fluid dynamics , Biomass , Segregation , Segregação , Fluidodinâmica