Influences of Mixing Ratios and Binder Types on Properties of Biomass Pellets

Barks and fruit peels usually considered residues are not seriously applied for any specific purpose. To add value to such agricultural wastes by using them as alternative solid fuels for thermo-chemical process are of interest. This research work aims at preparing biomass pellets from bark (eucalyptus), fruit shell (mangosteen) and fruit peel (papaya) using different binders (dammar, Persea kurzii kosterm powder, and cashew nut shell liquid). Influences of mass mixing ratio of eucalyptus bark: mangosteen shell: papaya peel (1:1:1, 2:1:1, 1:2:1, and 1:1:2) and binder on properties of the biomass pellets were investigated. The prepared pellets were also used as a fuel for the combustion process. The study results indicated that using cashew nut shell liquid as a binder provided the fuel pellets with rather short and non-uniform length while using dammar as a binder provided the pellets with fissures on the surface. Using the binder of Persea kurzii kosterm powder gave the pellets with significantly more uniform size, smoother surface, and higher density compared to using other binders) p<0.05). The pellets prepared using cashew nut shell liquid as a binder had the inferior mechanical properties (i.e., maximum force, maximum stress and yield strength) to those prepared using other binders)p<0.05). However, mixing ratio had no obvious influence on density and mechanical properties of the pellets. Binder types of the pellet fuels had strong effect on performances of the combustion system. Utilization of the pellets prepared using dammar as a binder showed the higher overall thermal efficiency of the combustion system than utilization of the pellets prepared using cashew nut shell liquid and Persea kurzii kosterm powder, respectively. The overall thermal efficiency of the combustion system was in the range of 24.838.5-%. (C) 2017 The Authors. Published by Elsevier Ltd.