Author(s)

Q. WANG, P. APAER, H. KUROKAWA & K. SUGIYAMA

Abstract

In this study, different carbonization processes were performed for thinning wood waste as organic industrial waste and forestry waste biomass to produce waste wood char, which is used as solid and gaseous fuel. Waste biomass samples were added to Na+ (NaOH) using thermogravimetry with a differential thermal analyser (TG/DTA), where the behaviour of thermal decomposition and the effect of additive amount of alkali metal were investigated. Waste wood char yields were increased at the peak temperature and weight loss was decreased with the increment of Na+ (NaOH) loaded value. The fixed carbon amount of waste wood char was also increased with the maximum Na+ (NaOH) loaded value at 100:1, and then it was decreased. Furthermore, in order to evaluate the effect of Na+ (NaOH) loaded value on char reactivity, an isothermal CO₂ gasification experiment was performed at temperatures between 700°C and 900°C for chars obtained by pyrolysis at 900°C. It was shown that the reaction rate was increased with increasing temperature and the reaction rate of raw char was markedly slower than Na+ (NaOH) loaded char. The activation energies of char were in decreasing trend with increasing Na loaded value. However, the activation energies of CO₂ gasification of char samples were conversely increased when Na+ loaded on char sample was more than 50:1. If too large amounts of Na+ (NaOH) were loaded on char sample, the rate of gasification reaction and the activation energy will be decreased as Na+ reacts with the char surface covering the gasifying agent.

Keywords

Alkali catalyst, biomass, carbonization, CO₂ gasification, energy recovery