Experimental studies on oil palm frond drying using swirling fluidized bed dryer

Abstract

Fluidized bed drying has become one of the preferred techniques in drying of agricultural products due to its thorough mixing ability and almost uniform moisture transfer from the product. This paper reports experimental studies on drying characteristics of chopped oil palm frond (OPF) when dried in a swirling fluidized bed dryer (SFBD). Unlike conventional fluidized beds, the SFBD is capable of fluidizing agricultural products which are fibrous and irregular in size and geometry, such as chopped OPF. Experiments were conducted to study the effect of hot air temperature ranging from 50°C to 80°C at a flowrate of 450 m 3 /hour, for two bed loadings. The OPF which consists of leaves and petiole (petiole) has different initial moisture contents of 57% and 70% respectively and dried to a final moisture content of 15%. Although higher temperatures of hot air result in rapid initial migration of moisture from the chopped OPF, the surface hardening due to shrinkage also becomes faster and hence limits further moisture removal prom the product. The OPF leaves and petiole exhibited different drying curves, suggesting the need for drying them separately unlike the current industrial practice for optimizing the drying process.

PTV profiling of particles motion from the top and side of a swirling fluidized bed

“…The annular spiral distributor was consisted of blades that were the truncated sectors of a circle with each blade inclined at an angle to the horizontal. A hollow metallic cone in the middle of the bed was used to avoid the accumulation of the particles and formation of the dead zone [12]. An important aspect of fluidization in SFBs is the shape and mass of the solid particles being used as bed material [13].…”