Kinetic study of oxy-combustion of plane tree (Platanus orientalis) seeds (PTS) in O2/Ar atmosphere

Abstract

The combustion reactivity of plane tree seeds biomass feedstock was studied using the thermogravimetry. The effects of atmosphere (O2/Ar) and different oxygen concentrations (O2/Ar = 20:80% and O2/Ar = 50:50%) on the combustion characteristics were investigated. When combustion atmosphere changes from O2/Ar = 50:50% to O2/Ar = 20:80% (reducing oxygen concentrations), the burnout temperature increases by 29.50 °C for tested biomass. Obtained results demonstrate the ease of ignition of investigated lignocellulosic material for O2/Ar = 50:50% ratio compared with O2/Ar = 20:80% ratio, and the actual trend is maintained under the condition when the heating rate increases. The reducing of oxygen concentration strongly influenced the amount of final residue products, particularly at higher heating rates (beyond 10 °C min−1). Kinetic analysis applied to investigated process shows strongly dependencies of both the apparent activation energy (E) and pre-exponential factor (logA) with conversion (α), especially in devolatilization and combustion of volatiles reaction stages. Large variation in E is attributed to existence of multiple parallel reactions. In order to solve this problem, the deconvolution technique that uses Fraser–Suzuki function was applied. It was shown that Fraser–Suzuki function fits successfully kinetic rate curves of entire combustion process, assuming the best selected nth-order reaction model.