Canola meal moisture-resistant fuel pellets: Study on the effects of process variables and additives on the pellet quality and compression characteristics

Abstract

This study focuses on pelletization of waste canola meal biomass to increase the bulk density, thereby reducing the transportation and storage costs, thus provide better material feeding in gasification reactors with less dust formation. The effects of feed constituents of canola meal such as protein, fiber, fat, lignin and feed moisture content as well as added binder, lubricant and densification process parameters on the strength and durability of the densified product are investigated. The increased durability (99%) of canola meal pellets was a result of added binder (5wt%) and the inherent protein (40wt%) and lignin (12wt%) content in the feed. From the compression data at different temperature and pressure, Kawakita and Lüdde model (1971) was developed to classify the feed material into groups. The R2 value ≥0.999 showed good model fit. It was found that at temperature >70°C, the particle undergoes rearrangement followed by fragmentation and particle plastic deformation during the compression process. The effects of coating agent on pellet durability, hardness and moisture uptake were studied to produce moisture-resistant pellets. Finally, the pellets were gasified in a fixed bed reactor using different gasifying agents such as steam, oxygen (O2) and carbon dioxide (CO2) and their effects were assessed. Carbon dioxide was found to give maximum carbon efficiency (CE) up to 82.7% and 50.7MJ/m3 LHV of gas at a temperature of 750°C and equivalence ratio (ER) of 0.4., whereas O2 gave 66.5% of CE with 44.7MJ/m3 LHV of gas at 650°C and 0.4 ER and steam produced gas with LHV 40.8MJ/m3 with CE 27.4% at 650°C and 0.2 ER. Thus, by producing moisture-resistant canola meal pellets with reasonable fuel characteristics, pelletization of canola meal provides a promising alternative for the utilization of canola meal waste as an alternative source of renewable energy.