Development And Performance Evaluation Of Rice Destoning Machine

2.9       Review of Existing Work on Rice Destoning Machine
Many researchers and scholars had worked on different types of rice destoning machine, among them are:
Okunola et al,. (2015). worked out on thedevelopment and evaluation of a cereal cleaner. The sieve assembly suspended by hangers experienced horizontal oscillation and small vertical motion thus displacing the grain from its stationary position to effect sorting and cleaning. During the test, the angle of tilt of the sieve was varied between 3 and 8° while the hanger angle and fan speed was maintained at 5° and 240 rpm respectively. The machine optimum performance was 98% product purity at a total separation efficiency of 71 % for Paddy rice at 3° tilt angle. Results indicated that paddy rice could be effectively separated from light materials of much lower terminal velocity and also from heavy materials like stones and leave stalks due to difference in geometrical and aerodynamic characteristics.
Ismail (2013) worked out on a design of a rice destoner. Reported that both sieves of the destoning are vibrated and  powered by a 0.50kW DC and rotational speed of 700rpm electric motor. The de-stonerhas the efficiency of 80% and mass flow rate of 2.10 kg/s which is equivalent to 7.50t/hr capacity.
Adewumi (1996) determine terminal velocities of some rice varieties grown in the South West of Nigeria; he gave the range of their mean values between5.06 to 5.19m/s and there were no significant differences among the different varieties.
Ogunlowo and Adesuyi(1999) determine the size, shape, density and suspension velocity of admixtures of ITA 257 rice variety and other impurities like stones and sticks and found that the sphericity of locally processed ITA 275 rice variety to be 0.41. Oguoma et al., (1992) determine the dimension of Abakaliki and Akeze rice. Their results showed 72% of the rice grains have length between 6.00 and 7.24mm, 23.3% have lengths between 5.25 and 5.99mm and 5% lengths 7.25 and 7.99mm. They also found that 99% of grains have thickness less than 2mm. The average loose bulk density of Abakaliki rice was found to be 0.818gcm-3, Akeze rice 0.785gcm-3at 10% moisture content. However, they did not specified whether it was on wet or dry basis.