Studies on the Drying Method of High Moist Naked Barley with Multi Layer Passing Type Dryer

Pre drying Application of Multi Layer Passing Type Dryer

Abstract

In order to investigate the adaptability and the utility of the multi-layer passing-type dryer for the pre-drying of naked barley, the drying characteristics tests with a miniature drying machine and the operational performance tests with a practical drying machine were made.
1. The drying characteristics tests with a miniature drying machine.
The processing efficiency and pearling aptitude with utilizing the miniture drying machine (Fig. 1) were investigated in different periods of harvest (in different moisture contents of grain) and forced air temperatures. Experiments were conducted under the constant condition of 0.3m³/s·100kg air flow rate and 3 layers.
1) Periods of harvest and properties of naked barley
This experiment was done in 1980, in which the ripeness of naked barley was delayed comparing with the common year, and the weather condition was unsettled in the periods of harvest (Fig. 2).
Therefore, the harvesting with head feeding combine had been necessalily practiced at the high moisture content of grain about 30-40% (Table 1).
2) Drying progress and the processing efficiency
The multi-layer passing-type dryer had been indicated high thermal efficiency in case of the high moist grain, and the exhaust air temperature of this dryer was nearly equal to the outside air temperature (Fig. 3). In case that the lower moist grain was piled, the moisture absorption had occurred in the top layer (Fig. 4).
The drying progress of the muhi-layer passing-type dryer was able to conjecture from the change of inlet and exhaust air condition (Fig. 5). The lower the moisture content of grain and the higher the forced air temperature, the shorter was the interval time of dumping (discharging), therefore the processing efficiency increased (Table 2). On the other hand, the drying rate of the grain piled in the top layer decreased and the moisture absorption remarkably appeared (Fig. 6).
3) Dignity and pearling aptitude
The grade of dignity and pearling aptitude was not so influenced by the period of harvest and forced air temperature. But, in the case of 75°C, the germination deteriorated in spite of the very short pre-drying time (Table 3).
2. The operational performance tests with a practical drying machine
The operational performance of the multi-layer passing-type dryer (Fig. 7) for pre-drying was investigated. From this experiment, it was comfirmed that the growth of blocking and the leavings of grain were nothing, and the pre-drying was efficiently achieved (Table 4, Fig. 8).
The total working hours of dumping and discharging was about 7.4 minutes (Table 5). For the high moist naked barley, it was estimated that the pre-drying capacity of a multi-layer passing-type dryer (4.0m² floor space) corresponded with 2-4 units of circulation type dryer of 2-2.5ton/unit.