Functional performance of a vertical-shaft centrifugal palm nut cracker

Abstract

Ndukwu M.C., Asoegwu S.N, 2010. Functional performance of a vertical-shaft centrifugal palm nut cracker. Res. Agr. Eng., 56: 77-83.A vertical-shaft centrifugal palm nut cracker was presented and evaluated. The cracker efficiency and kernel breakage ratio are some of the most important parameters for evaluating the cracker performance. From the result of this work, the two parameters are function of cracking speed, moisture content and feed rate. The result showed that for the lowest speed of 1,650 r/min, and the highest feed rate of 880 kg/h and for all moisture contents, the cracking efficiency was not up to 65%, therefore the efficiency increases with an increase in machine speed and a decrease in feed rate. The kernel breakage ratio ranged from 0-0.18 (0-18%) for all feed rates and moisture contents. It increased with moisture content and cracking speed, but decreased with feed rate. All the parameters determined have a linear relationship with moisture content.

A mathematical model for predicting the cracking efficiency of vertical-shaft centrifugal palm nut cracker

“…A centrifugal palm nut cracker prototype testing machine described in Ndukwu and Asoegwu (2010) was used in validating the model. The palm kernel cracker is powered by 1,600 kW electric motor and operates with centrifugal action.…”

“…The centrifugal action of the shaft flings the nut on the cracking ring with the nut cracking on impact. The palm kernel used in the experimental analysis is described in (Ndukwu, Asoegwu 2010) and is made up of a mixture of dura and ternara species of palm kernel. The diameters and thickness were determined with a vernier calliper reading up to 0.01 mm while the moisture content was determined in an oven.…”

“…The physical quantity affecting the cracking process includes both crop physical properties and machine parameters (Ndukwu 1998;Simonyan et al 2006;Asoegwu et al 2010). …”

“…The hammer impact type breaks or cracks the nut on impact when the hammer falls on it; while centrifugal impact nut cracker uses centrifugal action to crack the nut (Ndukwu, Asoegwu 2010). In the centrifugal impact type; the nut is fed into the hopper and it falls into the housing where a plate attached to the rotor is rotating; which flings the nut on the cracking ring; thereby breaking the nut.…”

“…Cracking therefore is an energy-involving process. According to some researchers (Asoegwu 1995;Ndukwu 1998) shelling or cracking has always posed a major problem in the processing of bio material and they attributed this to the shape and the brittleness of the kernel of the nut; rendering them susceptible to damageduring cracking. Presently most of the research work is tailored into modelling of the variables which determine the functionality of processing machines.…”