Torrefaction of Rice Husk using TG-FTIR and its Effect on the Fuel Characteristics, Carbon, and Energy Yields

A torrefaction testing method using TG-FTIR is presented, ensuring accuracy of torrefaction temperature and time. Torrefaction experiments of rice husk were performed at different temperatures (200, 230, 260, and 290 °C) for 30 min. The effect of torrefaction on the fuel characteristics was studied. Yields of carbon and oxygen, as well as solid and energy, were also considered. TG-FTIR analysis showed that in the depolymerization stage of the torrefaction process, CO2 characteristic peaks appeared, while those of carbonyl compounds and aromatic hydrocarbons were weaker. In the devolatilization stage, the characteristic peaks of CO2 and H2O were significant. Meanwhile, carbonyl compounds, aromatic hydrocarbons, and phenols were gradually produced. After that, each absorption peak gradually became weaker. After torrefaction at 290 °C, more than 76.6% of energy was retained in torrefied rice husk, while the solid yield was only 65.6%. 1.8%~52.2% of oxygen in rice husk was released in the torrefaction temperature range of 200 °C to 290 °C. Torrefaction increased the heating value, reduced the oxygen content, and improved the storability, which indicates that torrefaction is an effective way to improve the properties of rice husk.