Abstract
Extra low pressure ejector with fan pressure less than 300mmAq. were investigated on the characteristics of pneumatically conveying rice hull. In order to obtain the most suitable condition for conveying, as many as 340 experiments were carried on by varying nozzle diameter (Dn), diffuser dia. (Dd), static pressure (hf) and nozzle-diffuser distance (l). The following informations were obtained from the experiments;
(1) Conveying rate (W) with respect to l showed three types (Fig. 6) and the maximum W existed at the lbest
(2) Conveying air flow rate (Qa) showed lower value than supplied air flow rate (Qf) (Fig. 7), which means that a part of supplied air will blow out of the nozzle-diffuser gap. This makes smooth the hull supply by breaking a bridge of the hull.
(3) The l for the maximum W (lbest) was almost constant with respect to the opening ratio (Dd/Dn), but had a positive correlation with both Dn and hf.
(4) The opening ratios that had the maximum conveying rates were almost constant with respect to various static pressures (Fig. 8) but were plotted on a straight line with respect to the nozzle diameter change (Fig. 9).
(5) The values of maximum conveying rate had a positive correlation with both the nozzle diameter and the static pressure (Fig. 8).
(6) Conveying effectiveness that is defined as W/Pf was bigger at smaller static pressure with all diffusers other than the diameter 11.7mm (Fig. 10).
