The Design, Construction and Testing of a Vertical Squeeze Cassava Pulp Dewatering Machine

Abstract

Gari is a popular staple food in Nigeria. It is got from the dry frying of dewatered cassava pulp. Cassava is a plant which originated from South America but is now grown in most of the African countries. The Nigerian variety grows to a height of 0.6 to 2m. The root is the most useful part of the plant. It is about 35cm in length with a diameter of about 10cm in the mid part of the root and tapers to the end of the root. The roots which are brown are peeled. The inside which are white are soaked in water and allowed to ferment for about 3days. They were then grated and water added to about 80% moisture content to form the pulp. The cassava pulp was put into jute sack and tied for the test. Instead of the local method of stacking the pulp in sacks and puting heavy objects on top to dewater for two days, a motorized vertical squeeze dewatering machine was designed and fabricated to do the job of dewatering 200kg pulp in 33.72 minutes. This machine was 7 times quicker than the IITA multi-purpose press and 40 times quicker than the local method of dewatering. This was made possible by dewatering screws working with a total torque of 1182KNmm, a maximum principal stress of 100N/mm2, and a maximum shear stress of 60N/mm2. The pulp platform were transported up and down by action of screw followers. They operated with induced sheer stress in the screw and followers of 17.76 and 14.69N/mm2 which were adequately below the bearing pressure of 18N/mm2. The bevel gears were designed to carry static, dynamic and maximum tangential tooth load of 19.8, 1.07 and 9.05KN respectively. The rapid rate of dewatering will enhance the production of gari and thus assist development

Keywords

• pulp, dewater toxic, squeeze, cyanide, grate