CHANGES IN THE QUALITY OF SUPERHEATED STEAM DRIED OIL PALM EMPTY FRUIT BUNCHES FIBERS

Conventional drying of oil palm empty fruit bunches (EFB) fibers using flue gas from diesel burners frequently cause browning and dust explosion. Replacing the drying medium with superheated steam is expected to improve the quality of EFB fibers as well as improve the safety of the dryer. In this study, the effects of steam temperature and steam velocity on the quality of dried EFB fiber are investigated. The initial fiber moisture content is in the range of 0.96 to 1.0 g g^-1 dry basis. The drying experiment was carried out at atmospheric pressure, steam superficial velocity in the range of 0.3 to 0.49 m s^-1, and temperature in the range of 135 to 200°C. Three quality parameters of the EFB fibers, the color, strength and microstructure of the fibers were used to assess the changes in fiber quality as a result of superheated steam drying. The color is measured using a Minolta Chromameter. The fiber strength is measured using a testometric tensile machine. The microstructure of the fibers was viewed using a scanning electron microscopy (SEM). The color of the fiber was either improved or not significantly degraded. The strength of the fiber was also not significantly affected by the superheated steam drying. The microstructure was not significantly damaged by the temperature of superheated steam drying but was damaged by high steam velocity above 0.49 m^-1. Superheated steam drying is therefore found to improve the overall quality of EFB fibers compared to flue gas drying.