Optimization of palm shell pyrolysis parameters in helical screw fluidized bed reactor: Effect of particle size, pyrolysis time and vapor residence time

Abstract

The production of bio-oil from palm shell pyrolysis was investigated using a helical screw fluidized bed reactor setup. This study was done by investigating the effects of particle size, pyrolysis time and vapor residence time on pyrolysis product yields. The pyrolysis experiments were performed at different particle sizes, pyrolysis times and vapor residence times from 0.25 mm to 10 mm; 20 min to 60 min and 0.25 s to 15 s, respectively. The optimum condition for PS pyrolysis in helical screw fluidized bed reactor is at 2 mm particle size, 30 min pyrolysis time and 0.25 s vapor residence time to produce PS derived bio-oil of the highest yield of 73.86 wt% and higher heating value of 43.14 MJ/kg. Here, we report of the capability of helical screw fluidized bed reactor in handling large biomass particle size ranging up to 10 mm with marginal deteriorations of less than 1% and 3% for bio-oil yield and higher heating value respectively. This feature was attributed to the screw propeller design system in helical screw fluidized bed reactor which provided high mass and heat transfer at large particle size range which is 5 times of the particle size limit as recommended in previous studies. This finding would enable the possibility of helical screw fluidized based pyrolysis to be done in the absence of biomass size reduction processes to reduce process cost and complexity.