Effect of binding materials on physical and fuel characteristics of bagasse based pellets

Abstract

Growing energy demand and environmental issues are demanding the use of biomass based energy generation processes. However, inherent low bulk density of biomass poses problems of handling, storage and transportation which hinders its large scale application and demands its pretreatment. Pelletization process can address this inherent issue of biomass by converting it into a dense pellet having a regular shape and size. The strength of raw biomass pellet is very low and requires the use of binders. Therefore, in this study, cow dung and molasses were used as binders for the formation of bagasse based pellets. The effects of operating parameters, biomass composition, molasses concentration and drying time, on the physical and fuel characteristics of the pellets were studied and the response was recorded in terms of bulk density, pellet density, durability index, calorific value and proximate analysis. Based on experimental results, a significant trade off between durability index and calorific values of the pellets was observed and thus, the optimization of operating parameters was carried out. At optimal conditions, the pellet has the calorific value of 16.43 MJ kg−1 with 84.2% durability index. Subsequently, torrefaction of biomass was performed to upgrade the energy quality of the pellets. Thermal treatment resulted in 10% improvement in energy content of the biomass and also raised the durability of the pellet slightly. Moreover, the application of cow dung as a binder can be considered as a sustainable approach to improve the physical and fuel properties especially durability index of the pellets. Thus, these durable pellets can be used as a fuel in energy generation processes and for heating purposes in rural regions.