Investigation of Steam Treatment on the Sorption Behavior of Rice Straw Pellets

Abstract

Agricultural residue is a readily available biomass source for making biofuels. However, complex structure along with low calorific value makes it reluctant to be utilized. This necessitates the pretreatment of biomass to improve its accessibility. In this study, rice straws were treated with saturated steam at 180–200 °C for 5–10 min and pelletized. Results indicated that the pretreatment process could effectively improve the calorific values and enhance the hydrophobicity of the rice straws. The steam explosion process changed the content of chemical components in the biomass materials. With the increase of reaction temperature and retention time, the content of cellulose, hemicelluloses and lignin declined. Comparedwith the raw materials, there was an increase in the calorific value from 16.24 MJ/kg to 17.26 MJ/kg for the steam treated straws. For moisture sorption test under the condition of 30 °C and 90% relative humidity, the equilibrium moisture content dropped from 21% for untreated straw pellets to 14.2% for the steam treated straw pellets treated at 200 °C for 10 min. Moisture adsorption rate reduced along with the increase in steam temperature and retention time. This study demonstrated that steam explosion performed an effective way to improve the characteristics of agricultural residues.

Keywords

• steam explosion
• straw
• pellet
• calorific value
• moisture sorption