Dewatering behavior of wet oil palm sawn timber during flat compression

One obstacle to the industrial processing of oil palm wood is its nearly water-saturated state in green condition and its high tendency to develop cell collapse during kiln drying. This study analyzed mechanical dewatering by flat compression as an alternative pre-drying method for wet oil palm sawn timber. In the process, boards 700 mm long were compressed at ratios of 40% and 60% using a laboratory press, which resulted in water extraction of the free water varying between 38–52% and 60–73%, respectively. Since unperforated press plates were used, the water could only escape over the crosscut and long edges. The extent to which the crosscut and long edges were involved in dewatering was examined, and found to depend on the position of the board in the trunk due to the different water permeability conditions at the different heights. Permeability measurements, therefore, were carried out on cylindrical specimens using a specifically designed testing device. For the analysis of the hydrostatic pressure development in the boards, three pressure transducers were installed at different distances to the crosscut at half board thickness. The analysis of the recovery of compression showed, that the boards recovered to a large extend immediately after compression.