A small-scale extruder for Lumbang (Aleurites moluccana) oil extraction.
Abstract
The study evaluated and optimized a small-scale extruder with design of experiments following the Box and Benhken design resulting in 15 runs. The independent parameters included Lumbang temperature (30, 50 and 70 °C), quantity of Lumbang seeds fed to the hopper (50, 100, and 150 g) and speed of the screw shaft (165, 185 and 205 rpm) that evaluated the effects on the percentage oil recovery, percentage cake recovery, percentage oilcake recovery, extrusion efficiency, capacity and power consumption. Analysis of variance showed that the measured mean thickness of 0.91 in of the Lumbang seeds varied significantly from its mean length of 1.19 in and mean height of 1.19 in. A compressive strength test using the Universal Testing Machine showed that at 4.48 % moisture content, Lumbang seeds can withstand a maximum load of 1.08 kN before it reaches its yield point. Computed mean bulk density, angle of repose, particle density, rehydration rate and rehydration ratio were 0.42 kg/m3 , 25.63°, 0.997 g/mL, 0.10 g/hr and 60.39, respectively. Lowest angle of friction of 20.55° was attained at the metal plate, followed by 21.93° at the wooden surface along grains and lastly by 24.57° at the wooden surface across grains. The experimental results showed that the small-scale extruder had a percentage oil recovery range of 1.13 % to 7.29 %, percentage cake recovery of 30.04 % to 69.4 %, percentage oilcake recovery of 25.90 % to 66.74 %, extrusion efficiency of 2.15 % to 13.84 %, capacity of 127.38 g/hr to 254.59 g/hr, and a power consumption of 349.1 W to 361.5 W. A 95% confidence level was used in determining the significant effects of the independent variables with the response variables. The variation in the response was assumed to be due to effects in the independent factors, with random error accounting for the remaining variation. Analysis of variance showed that quantity and Lumbang temperature significantly affected the percentage oil recovery and efficiency. Quantity, on the other hand, significantly affected the capacity. Optimum conditions within the limits of the tested independent parameters indicated a Lumbang temperature of 50 °C, quantity of 150 g and screw shaft speed of 165 rpm. At these conditions, the predicted values for the oil recovery, cake recovery, oilcake recovery, efficiency, capacity and power consumption were 4.31 %, 62.36 %, 33.32%, 8.19 %, 169.12 g/hr and 351.4 W, respectively with a desirability value of 60%.