Effects of grain-receiving system on commingling in a country elevator
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The shift to quality-based marketing has challenged the grain-handling industry to meet desired purity levels as part of identity-preservation programs. Very few resources are available for the development of management strategies. This study measured commingling during grain transfer as influenced by the receiving configuration of an elevator. The facility, located at Manhattan, Kansas, has three receiving pits and one bucket elevator with a handling capacity of 190 t/h (metric ton per hour). The experiments involved moving soybeans through one of the receiving pits, followed by corn through the same flow path, without special cleaning between the two operations. Corn samples, collected at specific time intervals, were used to calculate commingling, the percentage by mass of soybean kernels mixed in corn. Commingling was greater than 1% only during the first 135 s (first 2 t, 2 metric ton, received), except for the gravity-type pit configuration where commingling remained in excess of 1% for the duration of the test (840 s or 73 t of grain). Measured mean cumulative commingling at the end of operation was 1.25%, 0.30%, and 0.23% for the combined effect of gravity-type pit and elevator leg, combined effect of elevator leg and pit with a drag conveyor, and effect of elevator leg, respectively. ARENA simulation was used to predict commingling using different levels of initial impurities of incoming grain. The model predicted that a 10-t load through a pit with drag conveyor would result in a cumulative commingling of 0.28%, of which 0.27% would be from the effect of the elevator leg.