Abstract:
The preconditioners heats, hydrates and mixes the dry raw materials before extrusion
and automatically doses the pre-treated product into the extruder. FUTA has developed
a floating fish feed extruder, however there is no locally available preconditioning system
that could enhance the floatability of the fish feed. Therefore a fish feed preconditioner was
designed, fabricated and tested to improve the quality and floatability of the feeds. The
machine consists of two insulated cylindrical barrel, paddles configuration on a shaft, frame,
hotwater and feed mash inlet, discharge chute, chain and sprocket. Various components of the
preconditioner
were
designed
using
standard
engineering
formulae.
The
preconditionerthroughput capacity is 650 kg/hr. It is poweredbya three-phase 11KW electric
motor which transmits power to the machines shaft and paddle configuration via chain and
sprocket. The effects of particle size and paddle rotating speed on mixing efficiency, final
moisture content and temperature of the preconditioned feed was evaluated. The machine was
evaluated using NIOMR feed formulation at feed mash particle sizes of 900 μm, 550 μm, 520
μm and paired paddle rotating speed of the lower and upper chamber at (96.8; 145.2), (122.6;
183.2) and(174.5; 260.8) rpm respectively.Hot water and feed mash were introduced into the
preconditioner simultaneously at rate of 2 litres per 13kg batch.The analysed results obtained
from the evaluation shows that at paired paddle speeds of (96.8; 145.2) rpm all the particulate
absorbed more moisture and temperature. There was a significant increase in temperature and
moisture content level of particles size 550 μm and 520 μmat all paired paddle rotating
speed.The uniformity of mix (mixing efficiency) at the lowest paired paddle speed was the
best with its Biot number averaging 0.1. The study suggests that appropriate combination of
the processing parameters will improve heating and hydration of feed particles in the
machine. The machine is recommended for use in feed production.
