Performance characterization and optimization of a synchronized medium scale oil palm fruit processing mill
Previous studies revealed that sterilization, digestion, and mechanical oil extraction have not been fully mechanized in Nigeria. A synchronized medium scale oil palm fruits processing mill consisting of a boiler, sterilizer, inclined screw conveyor, digester and screw press was developed. Prominent cultivars of Dura and Tenera fruitlets of 20, 30, and 50 years of age were selected for the evaluation of this mill. In this study, the performance evaluation of the unit operations of this mill was characterized. Surface response methodology was employed using STATISTICA Release 7 model: STA862D175437Q to optimize the mill throughput, efficiency and oil yield. The result showed that, the performance efficiency and throughput of boiler, sterilizer, inclined screw conveyor, vertical digester and twin cam screw press were 71.3% and 55.0 L/h, 70% and 75.4 kg/h, 72.7% and 70.2 kg/h, 85.4% and 152.4 kg/h, 83.0% and 190.0 kg/h, respectively. The synchronized medium scale oil palm processing mill had the optimum throughput, efficiency and oil yield of 80.35 kg/h, 84.70% and 29.28% respectively. Practical applications About 90% of annual palm oil production in Nigeria is still being processed with traditional and small scale methods across twenty four oil palm producing states. Over 40 million of rural women and small scale oil palm processors were grossly burdensome with lack of appropriate indigenous technology. It has been reported that about 140 of indigenous fabricators were involved in producing machines for small scale processors both in Nigeria and Ghana including palm oil research institutes, without developing a synchronized mill that can enhance productivity, timeliness and oil yield (Elekwachi, Fadare, Owolarafe, 2012; PIND, 2011) The unit operations of small scale mills were usually separately installed without instrumentation devices to regulate their processing parameters for optimum oil yield. In this synchronized medium scale oil palm fruits processing mill, fresh oil palm fruits were fully sterilized using the superheated steam generated from biomass fire tube vertical boiler which was synchronized with sterilizer. The sterilized fruits were conveyed through inclined screw conveyor to the steam jacketed digester, which was connected to the twin cam screw press for the hot extraction processing operation. It is a continuous and full sterilization mill, which has increased oil yield tremendously from 17.8% to 29.3% for Tenera cultivar fruitlets. This study presented technical information in term of mill equipment efficiency and throughput; likewise, the type of cultivar and age of palm fruit that enhances overall optimum mill efficiency and oil yield.