MARIGOLD PETAL THRESHING WITH OPEN VERSUS SECTORED ROTARY DRYERS

Abstract

Marigold petals can be detached from flowers by tumbling while being dried in a rotary heatedair dryer. Thisstudy examined the effect of dryer diameter, RPM, airflow, and flower compaction on threshing petals from marigold flowersusing two types of rotary dryers. A sectored rotary dryer was tested at three rotational speeds (2, 4, and 8 rpm) and twodiameters (1.2 and 1.8 m). An openchamber rotary dryer was tested with three levels of flower compaction (1.0, 1.5, and2.0 X) and three airflows (4.3, 4.5, and 5.3 changes/min). Both the sectored and open chamber dryers performed well in dryingand threshing petals from flowers. In most tests, more than 80% of the petals were threshed when their moisture dropped toless than 10%, i.e., within 20 to 24 h of drying.<br><br>Threshing performance was different between the sectored and open dryer. The sectored dryer had a relatively largeincrease in the threshing rate after 10 to 15 h of drying while the open dryers threshing rates remained fairly constant. Theopen dryer produced more threshed, high moisture petals. Threshed material from both dryers contained an insignificantamount of trash. The threshing characteristics for both dryer types were unaffected by changes in operating speed, amountof compaction, and airflow. However, by using higher compaction, the open dryer can thresh 50 to 100% more flowers.