Evaluation of physical and combustion characteristics of briquettes of palm fruit fibre and maize chaff using cassava extract as binder

Abstract

The selection or choice of agro-waste briquettes for domestic and industrial cottage applications depends on the fuel properties. In this work, Palm fruit fibre (PFF) and maize chaff were separately sun dried for seven days to remove moisture. The dried materials were separately ground using electric milling machine. They were then reduced to mesh sizes of 1.18, 1.70, 2.36 and 3.35 mm respectively. Filtered liquid extract of cassava was collected and dried for five days to form the binder. Different concentration of biomass materials were prepared by blending palm fruit fibre at 20, 40, 60 and 80% concentrations with maize chaff. Shattering index, ignition time, water boiling time, burning rate, specific fuel consumption, percentage ash content and calorific values of PFF and maize chaff briquettes were investigated. Results showed that shattering index reduced with increase in particle size and increased with reduction in particle size. Highest and lowest durability were obtained at particle sizes of 1.18 and 3.35 mm respectively. The ignition time decreased with increase in particle size of briquettes. 1.18 mm particles give the highest ignition time (54.88 sec.) and 3.35 mm particles gave the lowest ignition time (24.24 sec.). Therefore, increasing the particle size increases the ignitibility of the briquettes. It was observed that the ignition time increases with increase in percentage composition of palm fruit fibre in the briquette samples with a maximum ignition time of 29.66 seconds at 80% PFF. The specific fuel consumption, shows that there was an initial increase from 50.0 g/ltr to 55.0 g/ltr, after which it decreased continuously with increase in particle size. Water boiling time, showed an inverse relationship with particle size. However, water boiling time between 2.36 and 3.35mm particle size has a more pronounced variation in comparison with preceding values. Higher calorific value 31,514.05 and 31,004.30 kJ/kg of PFF and maize chaff briquettes were recorded.