Biomass from agriculture is a promising alternative fuel due to its carbon-neutral feature. However, raw biomass does not have properties required for its direct utilization for energy generation. Torrefaction is considered as a pretreatment method to improve the properties of biomass for energy applications. This study was aimed at investigating the effects of torrefaction temperature and residence time on some physical and chemical properties of torrefied corncobs. Therefore, a fixed-bed torrefaction reactor was developed and used in the torrefaction of corncobs. The torrefaction process parameters investigated were the torrefaction temperature (200, 240, and 280 °C) and the residence time (30, 60, and 90 min). The effects of these parameters on the mass loss, grindability, chemical composition, and calorific value of biomass were investigated. It was shown that the mass loss increased with increasing torrefaction temperature and residence time. The grinding throughput of the biomass was improved by increasing both the torrefaction temperature and the residence time. Torrefaction at higher temperatures and longer residence times had greater effects on the reduction in particle size of the milled corncobs. The calorific value was highest at a torrefaction temperature of 280 °C and a residence time of 90 min. The energy yield for all treatments ranged between 92.8 and 99.2%. The results obtained in this study could be useful in the operation and design of torrefaction reactors. They also provided insight into parameters to be investigated for optimization of the torrefaction reactor.

Efficient utilization of biomass requires conversion into forms that can be optimally applied in energy generation. Briquetting involves the compaction of biomass into solid blocks that are more efficient than raw biomass, and provides ease of transport and handling. These are improved when the briquettes possess a high density, shatter index, and compressive strength. Due to differences in nature and composition, it is imperative to define optimum conditions for the production of quality and durable briquettes for individual biomasses that are compacted into briquettes. This study investigated the effects of process variables on the strength, durability, and density of biomass briquettes produced using Abura sawdust. The lateral compressive strength and drop shatter index were investigated whilst varying the temperature (100–150 °C), pressure (9–15 MPa), and hold time (15–30 min). The compressive strength ranged between 2.06 and 5.15 MPa, whilst the shatter index was between 50 and 600. Briquette density was between 518.8 and 822.9 kg/m³. The pressure was significant to the determination of the compressive strength (p < 0.1) and the shatter index (p < 0.05). The pressure, temperature, and hold time are significant to the briquette density. Physical and mechanical characteristics of the binderless Abura sawdust briquettes can be improved by optimizing the densification variables during the briquetting process when moderate pressures are used for compaction.