Effect of some operating parameters on the performance of a pelleting press
Keywords:pelleting press, efficiency, durability, throughput capacity, bulk density, Response Surface Methodology (RSM), evaluation
One of the major challenges of fish pellets production at the micro and small scale level is the principal complement of equipment necessary for the local manufacture of the same. Imported fish pellets are quite expensive and unaffordable for the average fish farmer. Hence, the need to be able to produce fish feed at a lower cost yet achieving the objective of quantity and quality expected of pelleted feeds are paramount to the viability of the enterprise.
The aim of the study was to investigate the effects of some operating parameters (moisture content of the compounded feed, die speed of the press, and the feed rate) on the pelleting efficiency, throughput capacity, pellet durability and pellet bulk density and to optimise the conditions. Three moisture content levels (M1= 13, M2= 20 and M3 = 25% wet basis) of the compounded feed were used. For each of the moisture contents, two feed rates (Q1= 500, Q2= 350 kg/hr); and two die speeds (V1=200, and V2=250 r/min) were used for a die hole size of 4 mm. The effect of the independent parameters was significant for pellet efficiency, throughput capacity, pellet durability and pellet bulk density with R2 values of 0.9399, 0.9612, 0.8806 and 0.8977 respectively. This shows that the coefficient of determination is of positive correlation as determined from the ANOVA (Analysis of Variance) and the model equation. ANOVA was performed to check the adequacy of the fitted models. The response surface plots showing the interaction of variables were developed in Design-Expert 6.0.6 for every response, linear variables were found more significant than quadratic variables. Optimum conditions for maximum pellet efficiency, throughput capacity, pellet durability and bulk density corresponds to moisture content 25%, feed rate 499.99 kg/hr, speed 250 r/min with the desirability of 0.986. At this condition, pellet efficiency, throughput capacity, pellet durability and pellet bulk density were recorded as 95.7893%, 166.276 kg/hr, 98.0435% 0.846702 g/cm3 respectively.