A statistical analysis of the auto thermal fast pyrolysis of elephant grass in fluidized bed reactor based on produced charcoal

This research presents and discusses the results of product yields, higher heating value, proximate and ultimate analyses of the charcoal obtained in the Fast Pyrolysis Plant – PPR-200. It is a fast pyrolysis plant with a biomass feed capacity of 200 kg per hour, owned by Unicamp. Elephant grass with an average particle diameter of 2 mm and 12% of moisture was used as raw material. The PPR-200 facility operated under different conditions. Air was used as fluidization agent. This study tries to increase the knowledge of the PPR-200 plant operation in fast pyrolysis regimen. Experimental tests were carried out considering two independent factors: fluidization air and stoichiometric air ratio and the height of the fixed bed. In the pyrolysis process, a charcoal with a high carbon content is obtained as well as the release of oxygen from the biomass. Experimental results showed that the favorable operating conditions for oxygen release from elephant grass and carbon concentration in the charcoal are a fixed fluidized bed of 207 mm height and 8% of supplied air to the stoichiometric air ratio. Under these optimized conditions, the fluidized bed temperature resulted to be 650 °C on average and the yield production of charcoal in relation to the biomass fed (dry and ash free, d.a.f.) was of 14 wt.%. The charcoal produced under such conditions presented 92.4% of elemental carbon, and 2.85% of elemental oxygen.