Modeling the breakage stage in spheronization of cylindrical paste extrudates

Funder: The University of QueenslandAbstract: Spheronization of cylindrical extrudates on a rotating friction plate involves breakage and rounding. Little attention has been given to the breakage stage and quantitative modeling of this process is scarce. Two simple models are compared with experimental data obtained for the early stages of spheronization of microcrystalline cellulose/water extrudates. Tests were conducted for different times (t), rotational speeds (ω), initial loadings, and on pyramidal friction plates with different dimensions. The first model, describing the number of pellets, validated ω3t as a characteristic time scale for the breakage stage. The kinetic parameters obtained by fitting showed a systematic dependence on plate dimensions expressed as a scaled gap width. The second model, a simple population balance, described the evolution of the number and length of pellets. The pseudo rate constants provided insights into the kinetics: extrudates tended to break near the middle, while breakage of smaller pellets was slowed down by more pellet–pellet collisions

Compaction of palm kernel shell biochars for application as solid fuel

Palm oil is the most widely sold oil across the globe. The production of palm oil results in vast amounts of biomass waste. The palm kernel shells (PKS) can be used for energy production through gasification or combined heat and power (CHP). After gasification, some PKS remains as charred residue. In this manuscript, briquettes/pellets are produced from these biochars. The palm kernel shell biochars (PKSB) show very high calorific value exceeding typical values for biomass. The effects of water content, compaction pressure, feed particle size, compaction retention time, and the use of starch as a binder have been studied. The tensile crushing strength, impact resistance, and water resistance (immersion tests) show that the starch binder is imperative for suitable briquette quality. The use of starch increases the tensile crushing strength from less than 40kNm-2 to more than 800kNm-2 in the weakest (longitudinal) orientation. The tensile crushing strength of the starch-bound briquettes increases as their water content evaporates during storage and curing. It is speculated that the evaporation of water from the starch-bound sample allows for better cementing of the starch and PKSB particles

Modeling the breakage stage in spheronization of cylindrical paste extrudates

Funder: The University of QueenslandAbstract: Spheronization of cylindrical extrudates on a rotating friction plate involves breakage and rounding. Little attention has been given to the breakage stage and quantitative modeling of this process is scarce. Two simple models are compared with experimental data obtained for the early stages of spheronization of microcrystalline cellulose/water extrudates. Tests were conducted for different times (t), rotational speeds (ω), initial loadings, and on pyramidal friction plates with different dimensions. The first model, describing the number of pellets, validated ω3t as a characteristic time scale for the breakage stage. The kinetic parameters obtained by fitting showed a systematic dependence on plate dimensions expressed as a scaled gap width. The second model, a simple population balance, described the evolution of the number and length of pellets. The pseudo rate constants provided insights into the kinetics: extrudates tended to break near the middle, while breakage of smaller pellets was slowed down by more pellet–pellet collisions