Experimental tests of biomass fast pyrolysis in fluidized bed reactor criteria to system optimization

Author(s)

Juan Miguel Mesa Perez

• Document type: Doctoral Thesis
• Press: Campinas, SP. , gráficos, ilustrações, tabelas.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Agricola
• Defense date: 2004-07-12

Examining board members

Luís Augusto Barbosa Cortez; Luis Ernesto Brossard Perez; Manoel Regis Lima Verde Leal; Caio Glauco Sánchez; Isaias de Carvalho Macedo

• Advisor: Luís Augusto Barbosa Cortez
• Field of knowledge: Agronomical Sciences - Forestry Resources and Forestry Engineering
• Indexed in: Biblioteca Digital da UNICAMP
• Location: Universidade Estadual de Campinas. Biblioteca Central Cesar Lattes - Biblioteca da Área de Engenharia e Arquitetura; T/UNICAMP; M56t

Abstract

This research discusses a strategy to optimize and scale up the pyrolysis process in fluidized bed. The strategy uses adjusted mathematical models applied to the model reactor to the project commercial reactors. Several steps of that procedure were appraised based on the adjusted model for the percentage of elutriated fine charcoal in the model reactor. It was verified that, during the scale-up, the mathematical model was not effective; however it predicts problems associated to the change of scale. Exploratory tests were carried out to guarantee the stable operation of the reactor, which made possible the identification of the main problems related to the procedure during the fast pyrolysis in fluidized bed with atmospheric air. The possible causes of the problems, as well their solutions, are also analyzed. The greater difficulty in the operation was the leak of pyrolitic gases through the feeding system. The increase of the percentage of biomass stuffing of the feeding thread was the most effective solution to avoid gas leaking. When the reactor operation was stabilized, the influence of the percentage of air in relation to the stoichiometric and the height of the inert fixed bed on the quality characteristics and yield of the fine charcoal. That study allowed conclude that, for 8% of air in relation to the stoichiometric and 207 mm of the fixed sand bed height, the pyrolysis happens in a more intense way. The analysis was based on the principle that the pyrolysis process is a process to concentrate carbon in charcoal and release oxygen from the biomass. Finally, bio-oil samples were collected using a centrifugal separator and characterized. The viscosity and the insoluble content presented high values, when compared with the literature data. Based on those results, a system to bio-oil recovery was projected and built. It combines the direct contact followed by centrifugal separation (AU)