Date Palm Stone Pyrolysis and Gasification in a Bubbling Fluidized Bed Reactor

Abstract

The objective of this study is to investigate the potential of agricultural waste feedstock's as a biomass source. A large lab scale thermal-gravimetric fluidized bed reactor (TGFBR) was used to deduce kinetic parameters through measuring the dynamic mass changes of the overall thermal decomposition of biomass under isothermal conditions. The pyrolysis of date palm stones was studied in the TGFBR, and the kinetic expression was determined using a model fitting method. This work reveals that the reaction mechanism of the experimental thermal decomposition of palm stones was three-dimensional diffusion. The activation energy for experiments between 350°C and 600°C was 27.67 kJ/mole. By monitoring the mass variation from pyrolysis tests at different superficial velocities, the TGFBR also allowed deeper insight into suppression of diffusion control during thermal decomposition of biomass. To evaluate the effects of equivalence ratio (ER) and temperature on the product gas, the gasification of date palm stones was investigated at ER (0.15-0.35) and a temperature range of 600-750°C in 50°C increments. The hydrogen and carbon monoxide percentage, and heating value of the product gas, both increase with the increase in gasification temperature. Based on the energy yield (7 MJ/kg), the current results suggested that the optimum conditions were at T=750°C and ER=0.2. The information regarding pyrolysis and gasification is anticipated to be useful for researchers and end users, as well as drawing attention to date palm stones as an agricultural residue, which are valuable for use in alternative energy.