Modification and Performance Evaluation of a Horizontal Rotary Pulverizer-Sifter for Pressed cassava Cake in the production of Cassava Flour
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Date
2012
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Publisher
Obafemi Awolowo University
Abstract
Some component parts of the existing Horizontal Rotary Pulverizer-Sifter (HRP) was modified and the performance evaluation of the machine by varying some machine parameters. This was carried out with a view of improving the performance characteristics of HRP and its overall efficiency.
The hopper and sifting unit cover sizes were reduced; the rasping housing was enlarged; the grater abrasiveness was increased and the sifting screen surface was made abrasive. The performance of the machine was evaluated using a 3x3x3x3 completely randomized block design with the speed of rotary sifting screen at 30, 45 and 60 rpm; speed of the pulverizer at 500, 750 and 1000 rpm; moisture content at different times of pressing (6, 12, 18 hours) at 49.5, 47.0 and 46.2 % and screen sizes at 2, 3 and 5 mm. The Taguchi optimization methodology was used through L9 orthogonal array to suggest optimal combination of parameters affecting pulverization and sifting of dewatered cassava cake using horizontal rotary pulverizer-sifter. Data collected were also analyzed using inferential statistics with SAS statistical package.
The highest throughput capacity of 210.57 kg/h was obtained for Horizontal Rotary Pulverizer-Sifter (HRP) at the sifter speed of 60 rpm, pulverizer speed of 750 rpm, moisture content of 49.5 % and screen size of 5 mm. The highest percentage of recovered material was 85.58 % at the optimum conditions of 60 rpm sifter speed, 750 rpm pulverizer speed, 46.2 % moisture content and 5 mm screen size for the main effect. The maximum ‘siftable’ percentage of cassava cake introduced was 98.83 % at the optimum conditions of 30 rpm sifter speed, 500 rpm pulverizer speed, 46.2 % moisture content and 2 mm screen size of the mesh. All the parameters investigated have significant effect (p<0.01) on the pulverizing and sifting processes of cassava flour production.
Although the 5 mm screen size gave higher values of some performance characteristics than the 3 mm screen size, the 3 mm screen size is recommended by IITA for the production of high quality cassava flour. However, this research study revealed that the modified Horizontal Rotary Pulverizer-Sifter machine is effective and can be best operated at the optimum operational conditions of sifter speed of 60 rpm, pulverizer speed of 750 rpm and moisture content of 46.2 %.
Description
pages 127,xviii
Keywords
Horizontal Rotary Pulverizer-Sifter, Hopper, Taguchi Optimization Methodology, Cassava
Citation
OKE Oluseyi Olaolu (2012)Modification and Performance Evaluation of a Horizontal Rotary Pulverizer-Sifter for Pressed Cassava Cake in the Production of cassava Flavour